Journal ArticleJournal of Magnetic Resonance Open · September 1, 2025
Signal Amplification by Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei (SABRE-SHEATH) is an NMR hyperpolarization technique that relies of the simultaneous exchange of parahydrogen and a to-be-hyperpolarized molecule on the metal ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · June 2025
Signal Amplification By Reversible Exchange (SABRE) is a parahydrogen-based hyperpolarization technique that can generate orders-of-magnitude larger signals than thermal spin polarization within a minute. However, this method is limited by the availability ...
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Journal ArticleScience advances · February 2025
Coherent evolution is punctuated by dynamical processes such as chemical exchange, conformational transformation, or site hopping in many important problems ranging from biomolecular function to ion trap quantum computation. One well-explored example is nu ...
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Journal ArticleScience advances · December 2024
Carbon-based black pigments, a widely used class of pigments, are difficult to differentiate with the noninvasive techniques currently used in cultural heritage science. We use pump-probe microscopy, coupled with a support vector machine, to distinguish co ...
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Journal ArticleElectronic Structure · June 1, 2024
This paper reports and benchmarks a new implementation of nuclear magnetic resonance shieldings, magnetizabilities, and J-couplings for molecules within semilocal density functional theory, based on numeric atom-centered orbital (NAO) basis sets. NAO basis ...
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Journal ArticleProceedings of the National Academy of Sciences of the United States of America · April 2024
The inherently low signal-to-noise ratio of NMR and MRI is now being addressed by hyperpolarization methods. For example, iridium-based catalysts that reversibly bind both parahydrogen and ligands in solution can hyperpolarize protons (SABRE) or heteronucl ...
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Journal ArticleJphys Photonics · April 1, 2024
Cadmium sulfide (CdS) pigments have degraded in several well-known artworks, but the influence of pigment properties and environmental conditions on the degradation process have yet to be fully understood. Traditional non-destructive analysis techniques pr ...
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Conference2024 Conference on Lasers and Electro-Optics, CLEO 2024 · January 1, 2024
Melanoma, the most aggressive skin cancer, is responsible for around 10,000 deaths annually.Wearedevelopingadiagnosticbiomarkerbasedonfemtosecondpump-probemicroscopy of melanin, a natural pigment found in most melanoma. ...
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Conference2024 Conference on Lasers and Electro Optics CLEO 2024 · January 1, 2024
Melanoma, the most aggressive skin cancer, is responsible for around 10,000 deaths annually.Wearedevelopingadiagnosticbiomarkerbasedonfemtosecondpump-probemicroscopy of melanin, a natural pigment found in most melanoma. ...
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Journal ArticlePhysical Review A · July 1, 2023
The theoretical description of the interplay between coherent evolution and chemical exchange, originally developed for magnetic resonance and later applied to other spectroscopic regimes, was derived under incorrect statistical assumptions. Correcting the ...
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Journal ArticleJournal of Physics Communications · March 1, 2023
A recent paper in this journal presents magnetic resonance imaging (MRI) data on humans which are asserted to ‘suggest that we may have witnessed entanglement mediated by consciousness-related brain functions. Those brain functions must then operate non-cl ...
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Chapter · January 1, 2023
I won’t pretend I can write like Paul Muldoon. But I might be able to make more interesting pictures. Many of the spectacular achievements of twentieth-century science followed a simple paradigm. As new directions in basic atomic or molecular physics matur ...
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Journal ArticleThe journal of physical chemistry. A · December 2022
Hyperpolarized [1-13C]pyruvate is a revolutionary molecular probe enabling ultrafast metabolic MRI scans in 1 min. This technology is now under evaluation in over 30 clinical trials, which employ dissolution Dynamic Nuclear Polarization (d-DNP) ...
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Journal ArticleBioorganic & medicinal chemistry · October 2022
Nitric oxide (NO) is an important signaling molecule involved in a wide range of biological processes. Development of non-invasive, real-time detection of NO is greatly desired yet remains challenging. Here we report the design and development of novel
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · September 2022
Signal Amplification By Reversible Exchange (SABRE) and the heteronuclear variant, X-SABRE, increase the sensitivity of magnetic resonance techniques using order derived from reversible binding of para-hydrogen. One current limitation of SABRE is suboptima ...
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Journal ArticleOpt Express · August 29, 2022
Pump-probe microscopy of melanin in tumors has been proposed to improve diagnosis of malignant melanoma, based on the hypothesis that aggressive cancers disaggregate melanin structure. However, measured signals of melanin are complex superpositions of mult ...
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Journal ArticlePhysical chemistry chemical physics : PCCP · July 2022
SABRE (Signal Amplification by Reversible Exchange) methods provide a simple, fast, and cost-effective method to hyperpolarize a wide variety of molecules in solution, and have been demonstrated with protons and, more recently, with heteronuclei (X-SABRE). ...
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Journal ArticleScience advances · March 2022
Signal amplification by reversible exchange (SABRE) creates "hyperpolarization" (large spin magnetization) using a transition metal catalyst and parahydrogen, addressing the sensitivity limitations of magnetic resonance. SABRE and its heteronuclear variant ...
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Journal ArticlePhysical chemistry chemical physics : PCCP · March 2022
Hyperpolarization methods in magnetic resonance overcome sensitivity limitations, especially for low-γ nuclei such as 13C and 15N. Signal Amplification By Reversible Exchange (SABRE) and extended SABRE (X-SABRE) are efficient and low- ...
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Journal ArticleFront Oncol · 2022
Autophagy is characterized as a cytoprotective process and inhibition of autophagy with medicinally active agents, such as chloroquine (CQ) is proposed as a prospective adjuvant therapy for cancer. Here, we examined the preclinical effects of CQ combined w ...
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Journal ArticleChemical science · November 2021
Azide moieties, unique linear species containing three nitrogen atoms, represent an attractive class of molecular tag for hyperpolarized magnetic resonance imaging (HP-MRI). Here we demonstrate (15N)3-azide-containing molecules exhibi ...
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Journal ArticleOptics letters · March 2021
Pump-probe microscopy is an emerging nonlinear imaging technique based on high repetition rate lasers and fast intensity modulation. Here, we present new methods for pump-probe microscopy that keep the beam intensity constant and instead modulate the inter ...
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Journal ArticleSci Adv · September 2020
Mandates for mask use in public during the recent coronavirus disease 2019 (COVID-19) pandemic, worsened by global shortage of commercial supplies, have led to widespread use of homemade masks and mask alternatives. It is assumed that wearing such masks re ...
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Journal ArticleChemical communications (Cambridge, England) · August 2020
Here we report on chelating ligands for Signal Amplification By Reversible Exchange (SABRE) catalysts that permit hyperpolarisation on otherwise sterically hindered substrates. We demonstrate 1H enhancements of ∼100-fold over 8.5 T thermal for 2 ...
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Journal ArticleScience advances · August 2020
Many important applications in biochemistry, materials science, and catalysis sit squarely at the interface between quantum and statistical mechanics: Coherent evolution is interrupted by discrete events, such as binding of a substrate or isomerization. Th ...
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Journal ArticleOptics Express · April 13, 2020
We present a new imaging method for pump-probe microscopy that explores non-collinear excitation. This method (crossed-beam pump-probe microscopy, or CBPM) can significantly improve the axial resolution when imaging through low-NA lenses, providing ...
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Journal ArticleBioconjugate chemistry · March 2020
15N2-Diazirines represent an attractive class of imaging tags for hyperpolarized magnetic resonance imaging (HP-MRI), offering desirable biocompatibility, ease of incorporation into a variety of molecules, and ability to deliver long- ...
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Journal ArticleAngewandte Chemie (International ed. in English) · January 2020
Herein, we demonstrate "direct" 13 C hyperpolarization of 13 C-acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir-IMes; [IrCl(COD)(IMes)], (IMes=1,3-bis(2,4,6-trimethylphenyl), ...
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Journal ArticleAdvanced Materials · January 1, 2020
Herein, we demonstrate „direct“ 13C hyperpolarization of 13C-acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir-IMes; [IrCl(COD)(IMes)], (IMes=1,3-bis(2,4,6- trimethylphenyl), imidazole-2-ylidene; C ...
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Journal ArticleThe Journal of Chemical Physics · December 21, 2019
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The spatial heterogeneity of carrier dynamics in mixed halide perovskite CH3NH3PbI3−xClx thin films with a range of different chloride additions is mapped using femtosecond transient absorption microscopy (TAM). The comparison of TAM images of fibr ...
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Journal ArticleAdvanced Optical Materials · November 2019
AbstractThe spatial heterogeneity of carrier dynamics in polycrystalline metal halide perovskite (MHP) thin films has a strong influence on photovoltaic device performance; however, the underlying cause is not yet clearly u ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · October 2019
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Signal Amplification By Reversible Exchange, or SABRE, uses the singlet-order of parahydrogen to generate hyperpolarized signals on target nuclei, bypassing the limitations of traditional magnetic resonance. Experiments performed directly in the magnet pro ...
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Journal ArticleAngewandte Chemie (International ed. in English) · August 2019
Diazirine moieties are chemically stable and have been incorporated into biomolecules without impediment of biological activity. The 15 N2 labeled diazirines are appealing motifs for hyperpolarization supporting relaxation protected s ...
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Journal ArticleThe journal of physical chemistry letters · August 2019
We report on an extension of the quasi-resonance (QUASR) pulse sequence used for signal amplification by reversible exchange (SABRE), showing that we may target distantly J-coupled 19F-spins. Polarization transfer from the parahydrogen-de ...
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Journal ArticleJournal of the American Chemical Society · August 2019
A one-pot metal-free conversion of unprotected amino acids to terminal diazirines has been developed using phenyliodonium diacetate (PIDA) and ammonia. This PIDA-mediated transformation occurs via three consecutive reactions and involves an iodonitr ...
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Journal ArticleChemistry (Weinheim an der Bergstrasse, Germany) · July 2019
The NMR hyperpolarization of uniformly 15 N-labeled [15 N3 ]metronidazole is demonstrated by using SABRE-SHEATH. In this antibiotic, the 15 NO2 group is hyperpolarized through spin relays created by
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Journal ArticleThe Journal of chemical physics · July 2019
Featured Publication
Signal Amplification By Reversible Exchange (SABRE) and its heteronuclear variant SABRE in SHield Enables Alignment Transfer to Heteronuclei create large nuclear magnetization in target ligands, exploiting level crossings in an iridium catalyst that transi ...
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Journal ArticleScience Advances · June 2019
Pump-probe microscopy identifies metacinnabar and metallic mercury as possible degradation product of vermilion (α-HgS). ...
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Journal ArticleTransl Vis Sci Technol · May 2019
PURPOSE: We analyze melanin structure and biochemical composition in conjunctival melanocytic lesions using pump-probe microscopy to assess the potential for this method to assist in melanoma diagnosis. METHODS: Pump-probe microscopy interrogates transient ...
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Journal ArticleNature communications · January 2019
Signal amplification by reversible exchange (SABRE) is an efficient method to hyperpolarize spin-1/2 nuclei and affords signals that are orders of magnitude larger than those obtained by thermal spin polarization. Direct polarization transfer to heteronucl ...
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Journal ArticleACS applied materials & interfaces · November 2018
In this paper, we analyze fundamental photoexcitation processes and charge carrier kinetics in Cu2BaSnS4- xSe x (CBTSSe), a recently introduced alternative to Cu(In,Ga)(S,Se)2 and Cu2ZnSnS4- x
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Journal ArticleThe journal of physical chemistry letters · October 2018
Here we present the feasibility of NMR signal amplification by reversible exchange (SABRE) using radio frequency irradiation at low magnetic field (0.05 T) in the regime where the chemical shifts of free and catalyst-bound species are similar. In SABRE, th ...
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ConferenceICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · September 10, 2018
Diagnosis of melanoma is fraught with uncertainty, and discordance rates among physicians remain high because of the lack of a definitive criterion. Motivated by this challenge, this paper first introduces the Patch Weyl transform (PWT), a 2-dimensional va ...
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Journal ArticleScience advances · March 2018
Hyperpolarized magnetic resonance (HP-MR) is a powerful, sensitive, and noninvasive approach to visualize molecular structure, function, and dynamics in vitro and in vivo. Current applications of HP-MR mostly rely on hyperpolarization of target compounds i ...
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Journal ArticleLasers Med Sci · December 2017
The published online version contains mistake. Warren S. Warren was not included in the author group section. Corrected author group section is shown above. ...
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Journal ArticleThe journal of physical chemistry. C, Nanomaterials and interfaces · December 2017
A systematic experimental study is reported on the polarization transfer to distant spins, which do not directly bind to the polarization transfer complexes employed in Signal Amplification By Reversible Exchange (SABRE) experiments. Both, long-range trans ...
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Journal ArticleAngewandte Chemie (International ed. in English) · September 2017
Diazirines are an attractive class of potential molecular tags for magnetic resonance imaging owing to their biocompatibility and ease of incorporation into a large variety of molecules. As recently reported, 15 N2 -diazirine can be h ...
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Journal ArticleChemphyschem : a European journal of chemical physics and physical chemistry · August 2017
Fluorine-19 has high NMR detection sensitivity-similar to that of protons-owing to its large gyromagnetic ratio and high natural abundance (100 %). Unlike protons, however, fluorine-19 (19 F) has a negligible occurrence in biological objects, as ...
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Journal ArticleThe journal of physical chemistry letters · July 2017
Parahydrogen is an inexpensive and readily available source of hyperpolarization used to enhance magnetic resonance signals by up to four orders of magnitude above thermal signals obtained at ∼10 T. A significant challenge for applications is fast signal d ...
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Journal ArticleJournal of the American Chemical Society · June 2017
Signal amplification by reversible exchange (SABRE) is an inexpensive, fast, and even continuous hyperpolarization technique that uses para-hydrogen as hyperpolarization source. However, current SABRE faces a number of stumbling blocks for translation to b ...
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Journal ArticleChemphyschem : a European journal of chemical physics and physical chemistry · June 2017
Nuclear spin hyperpolarization techniques are revolutionizing the field of 13 C molecular MRI. While dissolution dynamic nuclear polarization (d-DNP) is currently the leading technique, it is generally slow (requiring ≈1 h) and costly (≈$USD10
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Journal ArticleJ Low Genit Tract Dis · April 2017
OBJECTIVES: Melanomas of the female genital tract present a unique clinical challenge. Not only are these lesions in an anatomically sensitive area, but also they tend to be multifocal and have high recurrence rates. Furthermore, several benign melanocytic ...
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Journal ArticleThe journal of physical chemistry. C, Nanomaterials and interfaces · March 2017
Signal Amplification by Reversible Exchange (SABRE) is a fast and convenient NMR hyperpolarization method that uses cheap and readily available para-hydrogen as a hyperpolarization source. SABRE can hyperpolarize protons and heteronuclei. Here we fo ...
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Journal ArticleScientific reports · November 2016
Pump-probe microscopy is an emerging technique that provides detailed chemical information of absorbers with sub-micrometer spatial resolution. Recent work has shown that the pump-probe signals from melanin in human skin cancers correlate well with clinica ...
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Journal ArticleChemistry (Weinheim an der Bergstrasse, Germany) · July 2016
NMR with thermal polarization requires relatively concentrated samples, particularly for nuclei with low abundance and low gyromagnetic ratios, such as (15) N. We expand the substrate scope of SABRE, a recently introduced hyperpolarization method, to allow ...
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Journal ArticleJournal of the American Chemical Society · July 2016
Direct NMR hyperpolarization of naturally abundant (15)N sites in metronidazole is demonstrated using SABRE-SHEATH (Signal Amplification by Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei). In only a few tens of seconds, nuclear sp ...
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Journal ArticleACS sensors · June 2016
15N nuclear spins of imidazole-15N2 were hyperpolarized using NMR signal amplification by reversible exchange in shield enables alignment transfer to heteronuclei (SABRE-SHEATH). A 15N NMR signal enhancement of ∼ ...
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Journal ArticleMagnetic resonance in medicine · May 2016
PurposeIntermolecular multiple quantum coherences (iMQCs) are a source of MR contrast with applications including temperature imaging, anisotropy mapping, and brown fat imaging. Because all applications are limited by signal-to-noise ratio (SNR), ...
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ConferenceOptics Infobase Conference Papers · April 18, 2016
Nonlinear pump-probe microscopy differentiates cutaneous, vulvar and conjunctival melanomas from less dangerous lesions, and can be used to assess metastatic potential. Applications in vivo (knockout mouse models) and in human biopsy are presented. ...
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Journal ArticleScience Advances · March 25, 2016
Conventional magnetic resonance (MR) faces serious sensitivity limitations which can be overcome by hyperpolarization methods, but the most common method (dynamic nuclear polarization) is complex and expensive, and applications are limited by short spin li ...
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Journal ArticleReview of Scientific Instruments · March 1, 2016
Multiphoton microscopy has rapidly gained popularity in biomedical imaging and materials science because of its ability to provide three-dimensional images at high spatial and temporal resolution even in optically scattering environments. Currently ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · February 2016
In this paper we demonstrate long-lived states involving a pair of chemically equivalent protons, with lifetimes ∼30 times T1 up to a total lifetime of ∼117s at high field (8.45T). This is demonstrated on trans-ethylene-d2 in solution, where magnetic inequ ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2016
The use of multiphoton interactions in biological tissue for imaging contrast requires highly sensitive optical measurements. These often involve signal processing and filtering steps between the photodetector and the data acquisition device, such as photo ...
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Journal ArticleBiomed Opt Express · September 1, 2015
Metastatic melanoma is associated with a poor prognosis, but no method reliably predicts which melanomas of a given stage will ultimately metastasize and which will not. While sentinel lymph node biopsy (SLNB) has emerged as the most powerful predictor of ...
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Book · July 14, 2015
THE PHYSICAL BASIS OF CHEMISTRY WARRENS. WARREN Professor of
Chemistry Princeton University ACADEMIC PRESS, INC. A Division of Harcourt
Brace & Company San Diego New York Boston London Sydney Tokyo Toronto ... ...
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Journal ArticleMagnetic resonance in medicine · July 2015
PurposeRed bone marrow metastases are common in breast and prostate cancer patients, but those metastases are currently incurable. Recent developments show that hyperthermia could be a successful treatment for bone metastasis, but thermometry rema ...
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Journal ArticleJ Biomed Opt · May 2015
We demonstrate a multimodal approach that combines a pump-probe with confocal reflectance and multiphoton autofluorescence microscopy. Pump-probe microscopy has been proven to be of great value in analyzing thin tissue sections of pigmented lesions, as it ...
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Journal ArticleThe journal of physical chemistry letters · May 2015
We report NMR Signal Amplification by Reversible Exchange (SABRE) hyperpolarization of the rare isotopes in "neat" liquids, each composed only of an otherwise pure target compound with isotopic natural abundance (n.a.) and millimolar concentrations of diss ...
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Journal ArticleThe journal of physical chemistry. C, Nanomaterials and interfaces · April 2015
NMR signal amplification by reversible exchange (SABRE) is a NMR hyperpolarization technique that enables nuclear spin polarization enhancement of molecules via concurrent chemical exchange of a target substrate and parahydrogen (the source of spin order) ...
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Journal ArticleReview of Scientific Instruments · March 1, 2015
The lock-in amplifier is a critical component in many different types of experiments, because of its ability to reduce spurious or environmental noise components by restricting detection to a single frequency and phase. One example application is p ...
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Journal ArticleJournal of the American Chemical Society · February 2015
Parahydrogen is demonstrated to efficiently transfer its nuclear spin hyperpolarization to nitrogen-15 in pyridine and nicotinamide (vitamin B(3) amide) by conducting "signal amplification by reversible exchange" (SABRE) at microtesla fields within a magne ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2015
Pump-probe microscopy is a multiphoton technique that generates molecular contrast from absorptive pigments, such as melanin. It holds the potential to be used as a non-invasive screening tool to discern whether a given early-stage melanoma has acquired th ...
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ConferenceProceedings of SPIE the International Society for Optical Engineering · January 1, 2015
We demonstrate that ultrafast pump-probe microscopy provides unique dynamics for natural iron oxide and iron hydroxide earth pigments, despite their chemical similarity. First, we conducted a pump-probe spectroscopy study on heat-treated hematite (the pure ...
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ConferenceProceedings of SPIE the International Society for Optical Engineering · January 1, 2015
The transient absorption response of melanin is a promising optically-accessible biomarker for distinguishing malignant melanoma from benign pigmented lesions, as demonstrated by earlier experiments on thin sections from biopsied tissue. The technique has ...
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ConferenceOptics Infobase Conference Papers · January 1, 2015
Enhanced control over femtosecond lasers (pulse shaping or pulse train modulation) improves contrast in tissue imaging. Pump-probe applications to melanoma diagnosis and cross phase modulation measurement in transparent tissues will be presented. ...
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ConferenceOptics Infobase Conference Papers · January 1, 2015
Pump-probe microscopy can extract molecular and structural contrast with high spatial resolution even in thick, scattering samples. We will discuss the technique’s principle and applications for imaging historic paintings and other cultural heritage object ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · November 2014
Nuclear spin hyperpolarization overcomes the sensitivity limitations of traditional NMR and MRI, but the most general method demonstrated to date (dynamic nuclear polarization) has significant limitations in scalability, cost, and complex apparatus design. ...
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Journal ArticleThe Journal of chemical physics · October 2014
In this paper we elucidate, theoretically and experimentally, molecular motifs which permit Long-Lived Polarization Protected by Symmetry (LOLIPOPS). The basic assembly principle starts from a pair of chemically equivalent nuclei supporting a long-lived si ...
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Journal ArticleJournal of the American Chemical Society · October 2014
Pairs of chemically equivalent (or nearly equivalent) spin-1/2 nuclei have been shown to create disconnected eigenstates that are very long-lived compared with the lifetime of pure magnetization (T1). Here the classes of molecules known to have accessible ...
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Journal ArticleProceedings of the National Academy of Sciences · February 4, 2014
SignificanceWe show that a nonlinear microscopy technique (femtosecond pump-probe microscopy) allows for nondestructive 3D imaging of paintings with molecular and structural contrast. Until now, studying the laye ...
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Journal ArticleThe journal of physical chemistry. A · February 2014
Ultrafast pump-probe measurements can discriminate the two forms of melanin found in biological tissue (eumelanin and pheomelanin), which may be useful for diagnosing and grading melanoma. However, recent work has shown that bound iron content changes eume ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · February 2014
Long-lived disconnected eigenstates (for example, the singlet state in a system with two nearly equivalent carbons, or the singlet-singlet state in a system with two chemically equivalent carbons and two chemically equivalent hydrogens) hold the potential ...
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Journal ArticleThe Journal of chemical physics · January 2014
Hyperpolarization methods, which can enhance nuclear spin signals by orders of magnitude, open up important new opportunities in magnetic resonance. However, many of these applications are limited by spin lattice relaxation, which typically destroys the hy ...
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Journal ArticleProgress in Biomedical Optics and Imaging Proceedings of SPIE · January 1, 2014
Pump-probe microscopy is a quantitative molecular imaging technique that yields diagnostically relevant information from endogenous pigments, like melanin, by probing their ultrafast photodynamic properties. Previously, the method was applied to image thin ...
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Journal ArticleJournal of biomedical optics · December 2013
Pump-probe microscopy is an emerging molecular imaging technique that probes the excited state dynamics properties of pigmented samples. This method has been particularly intriguing for melanoma because, unlike other methods available, it can provide nonde ...
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Journal ArticleInvest Ophthalmol Vis Sci · October 21, 2013
PURPOSE: To report the application of a novel imaging technique, pump-probe microscopy, to analyze patterns of pigment chemistry of conjunctival melanocytic lesion biopsies. METHODS: Histopathologic specimens of eight previously excised conjunctival melano ...
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Journal ArticleJ Am Chem Soc · July 3, 2013
Hyperpolarized magnetic resonance imaging (MRI) is a powerful technique enabling real-time monitoring of metabolites at concentration levels not accessible by standard MRI techniques. A considerable challenge this technique faces is the T1 decay of the hyp ...
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Journal ArticleJ Invest Dermatol · July 2013
Pump-probe microscopy nondestructively differentiates eumelanin and pheomelanin and can be used to quantify melanin distributions in thin biopsy slices. Here we have extended that work for imaging eumelanin and pheomelanin distributions on a subcellular sc ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · June 12, 2013
New labeling, imaging, or analysis tools could provide new retrospective insights when applied to archived, paraffinembedded samples. Deep-tissue multiphoton microscopy of paraffin-embedded specimens is achieved using optical clearing with mineral oil. We ...
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Chapter · June 7, 2013
We extend nonlinear pump-probe microscopy, recently demonstrated to image the microscopic distribution of eumelanin and pheomelanin in unstained skin biopsy sections, to the case of melanocytic conjunctival lesions. The microscopic distribution of pigmenta ...
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Journal ArticleThe journal of physical chemistry letters · June 2013
Melanins are biological pigments found throughout the animal kingdom that have many diverse functions. Pump-probe imaging can differentiate the two kinds of melanins found in human skin, eumelanin and pheomelanin, the distributions of which are relevant to ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · May 28, 2013
Phasor analysis has become a powerful tool for examining signals in fluorescence life-time microscopy (FLIM), where the analysis provides a fast, robust and intuitive means of separating different fluorescent species and mixtures thereof. In this work we a ...
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ConferenceCancer Research · April 15, 2013
AbstractRationale. One of the most lethal forms of skin cancer is the cutaneous melanoma that develops from melanocytes. Distinguishing between benign and malignant pigmented lesions is difficult and often r ...
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Journal ArticleMagnetic resonance in medicine · April 2013
Endogenous magnetic resonance contrast based on the localized composition of fat in vivo can provide functional information. We found that the unequal pulse timings of the Uhrig's dynamical decoupling multipulse echo sequences significantly alter the signa ...
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Journal ArticleMagnetic Resonance in Medicine · April 2013
We demonstrate a new method of using ultrasound data to achieve prospective motion compensation in MRI, especially for respiratory motion during interventional MRI procedures in moving organs such as the liver. The method relies on fingerprint‐like ...
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Journal ArticleOptics express · April 2013
Pump-probe microscopy is an imaging technique that delivers molecular contrast of pigmented samples. Here, we introduce pump-probe nonlinear phase dispersion spectroscopy (PP-NLDS), a method that leverages pump-probe microscopy and spectral-domain interfer ...
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Journal ArticleOptics InfoBase Conference Papers · January 1, 2013
Pump-probe nonlinear phase dispersion spectroscopy is a novel method that delivers molecular information of pigmented and non-pigmented samples by probing four dimensions: phase, amplitude, wavelength, and pump-probe time-delay. Its potential for molecular ...
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ConferenceOptics Infobase Conference Papers · January 1, 2013
Pump-probe nonlinear phase dispersion spectroscopy is a novel method that delivers molecular information of pigmented and non-pigmented samples by probing four dimensions: phase, amplitude, wavelength, and pump-probe time-delay. Its potential for molecular ...
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Journal ArticleJournal of Investigative Dermatology · 2013
Pump-probe microscopy nondestructively differentiates eumelanin and pheomelanin and can be used to quantify melanin distributions in thin biopsy slices. Here we have extended that work for imaging eumelanin and pheomelanin distributions on a subcellular sc ...
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Journal ArticlePloS one · January 2013
The recent discovery of active Brown Adipose Tissue (BAT) in adult humans has opened new avenues for obesity research and treatment, as reduced BAT activity seem to be implicated in human energy imbalance, diabetes, and hypertension. However, clinical appl ...
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ConferenceLaser Science Ls 2012 · December 1, 2012
Nonlinear optical pump-probe microscopy is able to sensitively extract excited state dynamics from historical art pigments. This technique allows three-dimensional imaging and characterization of different pigments, with far reaching applications for conse ...
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Journal ArticleFrontiers in Optics, FIO 2012 · December 1, 2012
Two-color pump-probe microscopy produces chemical contrast between melanins in skin. Increased eumelanin fraction corresponds with worse melanoma prognosis. The spatial heterogeneity of the melanin fraction, both on a cellular and sub-cellular scale, also ...
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Journal ArticleNature physics · November 2012
Long-lived nuclear spin states could greatly enhance the applicability of hyperpolarized nuclear magnetic resonance. Using singlet states between inequivalent spin pairs has been shown to extend the signal lifetime by more than an order of magnitude compar ...
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Journal ArticleICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · October 23, 2012
Melanoma detection relies on visual inspection of skin samples under the microscope via a qualitative set of indicators, causing large discordance among pathologists. New developments in pump-probe imaging enable the extraction of melanin intensity levels ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · October 2012
Improved understanding of the entrapment, transport, and release of drugs and small molecules within vesicles is important for drug delivery. Most methods rely on contrast agents or probe molecules; here, we propose a new MRI method to detect signal from w ...
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Journal ArticleThe Journal of chemical physics · May 2012
For more than three decades, the classical or mean-field picture describing the distant dipolar field has been almost always simplified to an effective field proportional to the local longitudinal magnetization, differing only by a scale factor of 1.5 for ...
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Journal ArticleProgress in Biomedical Optics and Imaging Proceedings of SPIE · April 16, 2012
A growing number of dermatologists and pathologists are concerned that the rapidly rising incidence of melanoma reflects not a true 'epidemic' but an increasing tendency to overdiagnose pigmented lesions. Addressing this problem requires both a better unde ...
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Journal ArticleCancer Research · April 15, 2012
AbstractRationale The diagnosis of melanoma is based on clinical identification followed by histopathologic confirmation. Surgical excision remains the mainstay for a suspicious lesion that will be evaluated ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · April 2012
To evaluate the efficiency and feasibility of intermolecular multiple quantum coherence (iMQC) magnetic resonance (MR) imaging for single cell detection, we obtained intermolecular double quantum coherence (iDQC) and conventional gradient echo (GE) images ...
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ConferenceFrontiers in Optics Fio 2012 · January 1, 2012
Two-color pump-probe microscopy produces chemical contrast between melanins in skin. Increased eumelanin fraction corresponds with worse melanoma prognosis. The spatial heterogeneity of the melanin fraction, both on a cellular and sub-cellular scale, also ...
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ConferenceOptics Infobase Conference Papers · December 1, 2011
Nonlinear imaging takes advantage of the localized nature of the interaction to achieve high spatial resolution, optical sectioning, and deeper penetration in tissue. However, nonlinear contrast (other than fluorescence or harmonic generation) is generally ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · July 25, 2011
Nonlinear imaging takes advantage of the localized nature of the interaction to achieve high spatial resolution, optical sectioning, and deeper penetration in tissue. However, nonlinear contrast (other than fluorescence or harmonic generation) is generally ...
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Journal ArticleBiomed Opt Express · June 1, 2011
We performed epi-mode pump-probe imaging of melanin in excised human pigmented lesions and both hemoglobin and melanin in live xenograft mouse melanoma models to depths greater than 100 µm. Eumelanin and pheomelanin images, which have been previously demon ...
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Journal ArticleJournal of lipid research · April 2011
We introduce an in vivo spectroscopic method to assess the effects of diet on fatty acid composition of the predominant chemical constituent of adipocytes in mice. To do this, we make use of a nonlinear NMR signal that, unlike a standard NMR signal, is int ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · April 2011
Intermolecular dipolar interactions between proton and carbon spins can be used to indirectly detect carbon spectra with high sensitivity. In this communication, we present a modified sequence that, in addition to the high sensitivity of heteronuclear inte ...
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Journal ArticleSci Transl Med · February 23, 2011
Melanoma diagnosis is clinically challenging: the accuracy of visual inspection by dermatologists is highly variable and heavily weighted toward false positives. Even the current gold standard of biopsy results in varying diagnoses among pathologists. We h ...
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Journal ArticleMagnetic resonance in medicine · February 2011
Brown adipose tissue and white adipose tissue depots are noninvasively characterized in vitro and in vivo in healthy and obese mice using intermolecular zero-quantum coherence transitions between lipid and water spins. Intermolecular zero-quantum coherence ...
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Journal ArticleNeoplasia (New York, N.Y.) · February 2011
A major challenge in cancer biology is to monitor and understand cancer metabolism in vivo with the goal of improved diagnosis and perhaps therapy. Because of the complexity of biochemical pathways, tracer methods are required for detecting specific enzyme ...
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ConferenceOptics InfoBase Conference Papers · December 1, 2010
We demonstrate a homodyne coherent anti-Stokes Raman scattering technique based on femtosecond laser pulse shaping (phase-cycling). This technique utilizes a self-generated non-resonant background as a local oscillator to retrieve phase information of the ...
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Journal ArticleOptics InfoBase Conference Papers · December 1, 2010
Two-color two-photon spectroscopy allows us for the first time to image the distribution of eumelanin and pheomelanin in tissue slices, giving histology-like detail and highlighting chemical and morphological changes in melanoma compared to benign lesions. ...
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Journal ArticleThe journal of physical chemistry. A · November 2010
Ultraviolet-visible spectroscopy readily discerns the two types of melanin pigments (eumelanin and pheomelanin), although fundamental details regarding the optical properties and pigment heterogeneity are more difficult to disentangle via analysis of the b ...
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Journal ArticleJ Magn Reson · June 2010
The development of accurate and non-invasive temperature imaging techniques has a wide variety of applications in fields such as medicine, chemistry and materials science. Accurate detection of temperature both in phantoms and in vivo can be obtained using ...
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Journal ArticleProc Natl Acad Sci U S A · February 23, 2010
Early and specific detection of metastatic cancer cells in the lung (the most common organ targeted by metastases) could significantly improve cancer treatment outcomes. However, the most widespread lung imaging methods use ionizing radiation and have low ...
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ConferenceOptics Infobase Conference Papers · January 1, 2010
We demonstrate a homodyne coherent anti-Stokes Raman scattering technique based on femtosecond laser pulse shaping (phase-cycling). This technique utilizes a self-generated non-resonant background as a local oscillator to retrieve phase information of the ...
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ConferenceOptics Infobase Conference Papers · January 1, 2010
Two-color two-photon spectroscopy allows us for the first time to image the distribution of eumelanin and pheomelanin in tissue slices, giving histology-like detail and highlighting chemical and morphological changes in melanoma compared to benign lesions. ...
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Journal ArticleInternational journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group · January 2010
PurposeA review of MRI temperature imaging methods based on intermolecular multiple quantum coherences (iMQCs) is presented. Temperature imaging based on iMQCs can provide absolute temperature maps that circumvent the artefacts that other proton f ...
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Journal ArticleThe Journal of chemical physics · November 2009
Fundamental optical and structural properties of melanins are not well understood due to their poor solubility characteristics and the chemical disorder present during biomolecular synthesis. We apply nonlinear transient absorption spectroscopy to quantify ...
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Journal ArticleThe Journal of chemical physics · November 2009
A recent quantum computing paper (G. S. Uhrig, Phys. Rev. Lett. 98, 100504 (2007)) analytically derived optimal pulse spacings for a multiple spin echo sequence designed to remove decoherence in a two-level system coupled to a bath. The spacings in what ha ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · June 1, 2009
Nonlinear microscopies (most commonly, two-photon fluorescence, second harmonic generation, and coherent anti-Stokes Raman scattering (CARS)) have had notable successes in imaging a variety of endogenous and exogenous targets in recent years. These methods ...
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Journal ArticleMaterials Science and Engineering C · May 5, 2009
This paper shows that superparamagnetic iron oxide nanoparticles (SPIONs) conjugated to luteinizing hormone releasing hormone (LHRH) (LHRH-SPIONs), can be used to target breast cancer cells. They also act as contrast enhancement agents during the magnetic ...
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Journal ArticlePhotochemistry and photobiology · May 2009
For the past two decades, nonlinear microscopy has been developed to overcome the scattering problem in thick tissue imaging. Owing to its increased imaging depth and high spatial resolution, nonlinear microscopy becomes the first choice for imaging living ...
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Journal ArticleMagnetic resonance in medicine · April 2009
Intermolecular double quantum coherences (iDQCs), signals that result from simultaneous transitions of two or more separated spins, are known to produce images that are highly sensitive to subvoxel structure, particularly local anisotropy. Here we demonstr ...
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Journal ArticleChemical Physics Letters · March 5, 2009
The observation of solvent-solute iZQC peaks is often hampered by strong nearby solvent peaks. Previous researchers have overcome this problem by adding conventional solvent suppression modules during the dipolar evolution time. Here we show that these sol ...
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Journal ArticleScience (New York, N.Y.) · March 2009
The sensitivity limitations for magnetic resonance imaging of organic molecules have recently been addressed by hyperpolarization methods, which prepare excess nuclear spin polarization. This approach can increase sensitivity by orders of magnitude, but th ...
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Journal ArticleJournal of Biological Physics · February 1, 2009
We present a summary of picosecond pump-probe and photon echo experiments in the mid-IR at 6 μm on the protein myoglobin. The intriguing temperature dependence of the amide I band in Mb is rather similar to the temperature dependence of the amide I band of ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · January 2009
Intermolecular multiple quantum coherences (iMQCs) can provide unique contrast with sub-voxel resolution. However, the characteristic growth rate of iMQCs mostly limits these effects to either hydrogen or hydrogen-coupled systems for thermally polarized sa ...
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Journal ArticleScience (New York, N.Y.) · October 2008
Conventional magnetic resonance methods that provide interior temperature profiles, which find use in clinical applications such as hyperthermic therapy, can develop inaccuracies caused by the inherently inhomogeneous magnetic field within tissues or by pr ...
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Journal ArticleJournal of biomedical optics · September 2008
As some of the most ubiquitous and biologically important natural pigments, melanins play essential roles in the photoprotection of skin. Changes in melanin production could potentially be useful for clinical diagnosis of the progression stage of melanoma. ...
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Journal ArticleThe Journal of chemical physics · August 2008
This report introduces a new approach that enhances nonlinear solution magnetic resonance signals from intermolecular dipolar interactions. The resulting signals can theoretically be as large as the full equilibrium magnetization. Simple, readily implement ...
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Journal ArticleJournal of biomedical optics · July 2008
The ability to perform high-resolution imaging of microvasculature and its oxygenation is very important in studying early tumor development. Toward this goal, we improved upon our excited state absorption (ESA)-based imaging technique to allow us to not o ...
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Journal ArticleProgress in Biomedical Optics and Imaging Proceedings of SPIE · April 21, 2008
As a main pigment in skin tissues, melanin plays an important role in photo-protecting skin from UV radiation. However, melanogenesis may be altered due to disease or environmental factors; for example, sun exposure may cause damage and mutation of melanoc ...
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Journal ArticleProgress in Biomedical Optics and Imaging Proceedings of SPIE · April 21, 2008
We have demonstrated a new optical microscopy technique for imaging microvasculature without any labeling. With a very sensitive two-color excited state absorption (ESA) measurement method, we demonstrated that oxy-hemoglobin and deoxy-hemoglobin show dist ...
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Journal ArticleThe Journal of chemical physics · April 2008
We examine the propagation of shaped (amplitude- and frequency-modulated) ultrafast laser pulses through optically dense rubidium vapor. Pulse reshaping, stimulated emission dynamics, and residual electronic excitation all strongly depend on the laser puls ...
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ConferenceOptics Infobase Conference Papers · January 1, 2008
We have designed an interferometric acousto-optic pulse shaper capable of shaping individual pulses differently from a mode-locked laser. The design enables the measurement of weak nonlinear optical signals at megahertz (MHz) rates for imaging applications ...
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ConferenceOptics Infobase Conference Papers · January 1, 2008
Recently developed ultrafast laser pulse shaping technology allows highsensitivity measurements of nonlinear optical effects in highly scattering media. We present applications of these techniques to extract intrinsic structural, metabolic and functional c ...
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ConferenceOptics Infobase Conference Papers · January 1, 2008
Using novel femtosecond laser pulse shaping techniques and a virtually background-free detection strategy we demonstrate strong self-phase modulation signatures of neuronal activity in hippocampal brain slices without the use of exogenous contrast agents. ...
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Journal ArticleOpt Lett · September 15, 2007
We demonstrate that both oxyhemoglobin and deoxyhemoglobin have sequential two-color, two-photon absorption properties that can serve as endogenous contrasts in microvasculature imaging. Using a sensitive modulation transfer technique, we are able to image ...
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ConferenceProgress in Biomedical Optics and Imaging Proceedings of SPIE · September 3, 2007
Even though multi-photon fluorescence microscopy offers higher resolution and better penetration depth than traditional fluorescence microscopy, its use is restricted to the detection of molecules that fluoresce. Two-photon absorption (TPA) imaging can pro ...
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Journal ArticleJournal of biomedical optics · September 2007
We develop a new approach in imaging nonfluorescent species with two-color two-photon and excited state absorption microscopy. If one of two synchronized mode-locked pulse trains at different colors is intensity modulated, the modulation transfers to the o ...
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Journal ArticleProgress in Biomedical Optics and Imaging Proceedings of SPIE · August 31, 2007
We have demonstrated a new method for imaging melanin with two-color excited state absorption microscopy. If one of two synchronized mode-locked pulse trains at different colors is intensity modulated, the modulation transfers to the other pulse train when ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · July 2007
Many of the promising applications of the CRAZED (COSY Revamped with Asymmetric Z-gradient Echo Detection) experiments are in biomedical and clinical technologies. In tissue, however, signal from the typical CRAZED experiment is largely limited by transver ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · July 2007
Transport of water and ions through cell membranes plays an important role in cell metabolism. We demonstrate a novel technique to measure water transport dynamics using erythrocyte suspensions as an example. This technique takes advantage of inhomogeneous ...
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Journal ArticleLaser Focus World · June 1, 2007
Femtosecond laser pulse and pulse-train shaping allow detection of new nonlinear effects, with modest powers, making new biomarkers accessible and permitting deeper tissue imaging than conventional microscopy. The most developed of these technique create l ...
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Journal ArticleMagnetic resonance imaging · June 2007
Most imaging studies using intermolecular multiple-quantum coherences (iMQCs) have focused on the two-spin dipolar interactions--zero and double quantum coherences. Here, we report the results of various experimental studies to assess the feasibility of ma ...
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Journal ArticleThe Journal of chemical physics · April 2007
In this paper the authors compare 400 nm one-photon and 800 nm two-photon two-dimensional Fourier transform electronic spectra of the organic laser dye Coumarin 102 in methanol using collinear optical pulse sequences and phase cycling. Results from the two ...
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Journal ArticleAip Conference Proceedings · December 1, 2006
Nearly a decades' worth of experimental efforts on solution NMR quantum computing have confirmed that such systems will not be scalable to a useful number of qubits, completely consistent with quantum mechanical predictions in 1997. However, the theoretica ...
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ConferenceProceedings of SPIE the International Society for Optical Engineering · May 8, 2006
Multiphoton excitation fluorescence microscopy has proven to be a powerful method for non-invasive, in vivo, thick tissue imaging with molecular specificity. However, many important endogenous biomolecules do not fluoresce (NAD) or fluoresce with low effic ...
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Journal ArticleOptics Letters · January 15, 2006
We report all-UV coherent anti-Stokes Raman scattering (CARS) in calcite with 250-280 nm pump, Stokes, probe, and anti-Stokes light. UV CARS efficiency is ∼7X higher than for comparable scattering in the visible, 480-540 nm. Time-resolved UV CARS reveals l ...
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Journal ArticleOptics InfoBase Conference Papers · January 1, 2006
We show that femtosecond shaped pulses can be used to detect coherent and stimulated Raman scattering in multi-scattering media. It is possible to perform Raman spectroscopy with such specially shaped pulses to determine vibrational frequencies and relaxat ...
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Journal ArticleOptics Infobase Conference Papers · January 1, 2006
We show that femtosecond shaped pulses can be used to detect coherent and stimulated Raman scattering in multi-scattering media. It is possible to perform Raman spectroscopy with such specially shaped pulses to determine vibrational frequencies and relaxat ...
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Journal ArticleOptics Infobase Conference Papers · January 1, 2006
We show that femtosecond shaped pulses can be used to detect coherent and stimulated Raman scattering in multi-scattering media. It is possible to perform Raman spectroscopy with such specially shaped pulses to determine vibrational frequencies and relaxat ...
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Journal ArticleOptics Infobase Conference Papers · January 1, 2006
We show that femtosecond shaped pulses can be used to detect coherent and stimulated Raman scattering in multi-scattering media. It is possible to perform Raman spectroscopy with such specially shaped pulses to determine vibrational frequencies and relaxat ...
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Journal ArticleOptics Infobase Conference Papers · January 1, 2006
Time-resolved, coherent anti-Stokes Raman scattering from internal vibrations in calcite is reported with all the wavelengths in the ultraviolet. Two-photon absorption, excitation-dependent dephasing times, and a comparison of ultraviolet and visible effic ...
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ConferenceOptics Infobase Conference Papers · January 1, 2006
We show that femtosecond shaped pulses can be used to detect coherent and stimulated Raman scattering in multi-scattering media. It is possible to perform Raman spectroscopy with such specially shaped pulses to determine vibrational frequencies and relaxat ...
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ConferenceOptics Infobase Conference Papers · January 1, 2006
We show that femtosecond shaped pulses can be used to detect coherent and stimulated Raman scattering in multi-scattering media. It is possible to perform Raman spectroscopy with such specially shaped pulses to determine vibrational frequencies and relaxat ...
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Journal ArticleJournal of the American Chemical Society · December 2005
Clinical magnetic resonance spectroscopy is typically limited by magnetic inhomogeneities which destroy spectral resolution, but intermolecular zero quantum coherences (iZQCs) are insensitive to such inhomogeneities. iZQC resolution in vivo, however, has b ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · September 2005
We investigate the use of intermolecular multiple-quantum coherence to probe structural anisotropy in trabecular bone. Despite the low volume fraction of bone, the bone-water interface produces internal magnetic field gradients which modulate the dipolar f ...
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Journal ArticleProceedings of the National Academy of Sciences of the United States of America · May 31, 2005
We show that gain-swept superradiance can be used to detect low (parts per million) concentrations of various gases at distances on the order of kilometers, which is done by using pulse timing to create small regions of gain at positions that sweep toward ...
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Journal ArticleOptics Express · May 15, 2005
Two dimensional magnetic and optical spectra contain information about structure and dynamics inaccessible to the linear spectroscopist. Recently, phase cycling techniques in optical spectroscopy have extended the capabilities of two-dimensional electronic ...
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Journal Article2005 Conference on Lasers and Electro Optics CLEO · January 1, 2005
Time-resolved, coherent anti-Stokes Raman scattering from internal vibrations in calcite is reported with all the wavelengths in the ultraviolet. Two-photon absorption, excitation-dependent dephasing times, and a comparison of ultraviolet and visible effic ...
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Journal ArticleAdvances in experimental medicine and biology · January 2005
It is proposed that the redox state of mitochondrial NADH will complement blood gas analysis for measuring the health and welfare of human tissues. Use of arterial oxygen saturation levels (SaO2), especially as assayed by the Nellcor instrument, has spread ...
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Journal ArticleOptics Infobase Conference Papers · January 1, 2005
Time-resolved, coherent anti-Stokes Raman scattering from internal vibrations in calcite is reported with all the wavelengths in the ultraviolet. Two-photon absorption, excitation-dependent dephasing times, and a comparison of ultraviolet and visible effic ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 21, 2004
Terahertz (T-Rays) spectroscopy has recently emerged as a powerful method to access a heretofore barely explored region of the electromagnetic spectrum where fundamental molecular resonances occur. Besides their importance for fundamental research, these r ...
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ConferenceSpringer Series in Chemical Physics · December 1, 2004
Femtosecond laser pulse shaping permits background-free detection of two-photon absorption, which tends to refill spectral holes. This opens up new spectroscopic windows for monitoring tissue characteristics. ...
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Journal ArticleMagnetic resonance imaging · December 2004
Until recently, NMR imaging with intermolecular multiple-quantum coherences (iMQCs) has been based on the acquisition of a single echo. In vivo studies of iMQC image contrast would greatly benefit from a method that could acquire several orders of quantum ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 2004
Acousto-optic modulator (AOM)-based pulse shaping permits precise spectrum slicing, which is useful for dense wavelength division multiplexed (DWDM)-based architectures. In essence, this method uses microsecond-duration radio frequency pulses to completely ...
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Journal ArticleThe Journal of chemical physics · October 2004
Turbulent spin dynamics arising from the joint action of radiation damping and the distant dipolar field are shown to generate irreproducible measurements in popular high-field, gradient-based magnetic resonance (MR) experiments, undermining the prevailing ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · October 2004
The dependence of the bulk signal intensity from a CRAZED NMR pulse sequence on magnetic field gradient strength and direction as a method to probe the geometry of porous materials is investigated. In this article, we report on the reconstruction of three- ...
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Journal ArticlePhysics Letters Section A General Atomic and Solid State Physics · May 31, 2004
Using intermolecular multiple-quantum coherence (iMQC) we report the first observation of Bragg-like diffraction via multiple distantly coupled nuclear spins. A compact quantum-mechanical formalism has been developed for analytically calculating iMQCs. The ...
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ConferenceOptics Infobase Conference Papers · January 1, 2004
We present a new method for deep tissue imaging using nonlinear optics. Specific tailored laser pulses permit measurement of two-photon absorption or self-phase modulation with modest near-IR powers (1-10 mW), giving good penetration and molecular specific ...
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ConferenceOptics Infobase Conference Papers · January 1, 2004
Femtosecond laser pulse shaping permits background-free detection of two-photon absorption, which tends to refill spectral holes. This opens up new spectroscopic windows for monitoring tissue characteristics. ...
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Journal ArticlePhysical Review B Condensed Matter and Materials Physics · January 1, 2004
Averaged Bloch equations for magnetization evolution in a biphasic heterogeneous material with periodic structures are derived using a two-scale asymptotic expansion. Upscaling of the partial differential equations with microscopic boundary conditions resu ...
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Journal ArticleChemical Physics Letters · January 1, 2004
The effect of pulse propagation on the lineshape in a two-dimensional photon echo spectrum is investigated using the coupled Maxwell Bloch equations. Reshaping of excitation and signal pulses due to propagation results in broadening of peak profiles. The a ...
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Conference2004 2nd IEEE International Symposium on Biomedical Imaging Macro to Nano · January 1, 2004
Multiphoton imaging with fluorescence detection has proven to be a powerful method for moderately deep tissue imaging (less than 1 mm) with molecular specificity. However, many important endogenous biomolecules do not fluoresce (NAD) or with low efficiency ...
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Journal ArticleJournal of Modern Optics · January 1, 2004
We present experimental evidence of a resonant coherent anti-Stokes Raman spectroscopy (CARS) signal from dipicolinic acid, a marker molecule in anthrax spores. We also show some evidence of resonant CARS signal associated with the 1000 cm−1 resonance from ...
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Journal ArticleJournal of Modern Optics · January 1, 2004
Phase-matching techniques are widely used to retrieve nonlinear optical signals of electronic and vibrational transitions. Here, collinear, phase cycled pulses are used to collect the same nonlinear signals in direct analogy to nuclear magnetic resonance s ...
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Journal ArticleConference Proceedings Lasers and Electro Optics Society Annual Meeting LEOS · December 9, 2003
An overview is given of experimental results towards the realization of an alternative optical technique, the FAST CARS (Femtosecond Adaptive Spectroscopic Technique for Coherent Anti-Stokes Raman Spectroscopy) approach. This proposal makes use of the CARS ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 2003
We discuss the role of evolutionary adaptive algorithms in shaping femtosecond pulses with an eye toward their use in the quantum control of optical properties. In particular, we report preliminary results from an ongoing attempt to implement the recently ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 2003
Optical techniques are very promising for detecting and identifying bacterial spores. They are potentially superior to the existing "wet chemistry" approaches regarding several important features of an effective alarm system, such as speed, in-field use, c ...
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Journal ArticleMagnetic resonance imaging · December 2003
Various analogs of NMR and MRI are now technically possible in optics; specifically, high-resolution laser-pulse shaping and complex pulse sequence generation with well-defined phase shifts has been demonstrated. Here we summarize this technology and discu ...
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Journal ArticleMagnetic resonance imaging · December 2003
Recent studies have demonstrated the ability to detect images based on intermolecular multiple-quantum coherences (iMQCs) that correspond to flipping of two or more separated spins simultaneously, as opposed to conventional magnetic resonance where only on ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · December 2003
Intermolecular multiple-quantum coherence (iMQC) MR imaging provides a fundamentally different contrast mechanism. It allows probing tissue microstructure by tuning the direction and strength of the correlation gradient. However, iMQC images of a specific ...
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Journal ArticleJournal of Chemical Physics · August 22, 2003
A perturbative method was used to investigate the effect of propagation on multilevel systems, specifically on the relative intensity and profile of the cross peaks. It was shown that both the peak profiles and the relative intensity of the peaks in a 2D s ...
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Journal ArticleScience (New York, N.Y.) · June 2003
Femtosecond phase-coherent two-dimensional (2D) spectroscopy has been experimentally demonstrated as the direct optical analog of 2D nuclear magnetic resonance. An acousto-optic pulse shaper created a collinear three-pulse sequence with well-controlled and ...
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Journal ArticleJournal of the Optical Society of America B Optical Physics · January 1, 2003
A study is performed on relative-phase ambiguities in measurements of ultrashort pulses with well-separated multiple frequency components. It is shown that if a laser pulse consists of components that are well separated in the frequency domain, the self-re ...
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Journal ArticleOptics Express · January 1, 2003
We produce microjoule energy shaped mid infrared (MIR) pulses in an optical parametric amplification (OPA) process by imposing the phase and amplitude profile of an arbitrarily shaped pump pulse onto the idler pulse. Using phase locked pulses created using ...
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Journal ArticleJournal of the Optical Society of America B Optical Physics · January 1, 2003
We demonstrate an all-optical intensity noise reduction technique by using two-photon absorption of ZnSe in a Z-scan configuration. We measure the nonlinear transmission and the shot-to-shot energy fluctuations of 860-nm intense femtosecond laser pulses. A ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 2003
We create arbitrarily shaped ultrashort pulses in the mid infrared (∼3.0μm). The amplitude and phase profile of a shaped broadband near infrared signal pulse is transferred to the mid infrared idler pulse in a KNbO3 optical parametric amplificat ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 2003
Phase sensitive measurement of two-photon induced coherence is demonstrated, using phase coherent pulse pairs. By using an acousto-optic pulse shaper the different coherence transfer pathways in the two-photon absorption process can be separated. ...
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Journal ArticleMagnetic resonance in medicine · December 2002
In vivo and ex vivo MRI based on intermolecular multiple-quantum coherences (iMQC) is predicted to provide a fundamentally different source of contrast for MRI. This article investigates the dependence of image contrast upon the choice of correlation dista ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 2002
The joint action of two readily observed effects in solution magnetic resonance- radiation damping and the dipolar field-are shown to generate spatiotemporal chaos in routine experiments. The extreme sensitivity of the chaotic spin dynamics to experimental ...
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Journal ArticleOptics Letters · September 15, 2002
We demonstrate a direct and sensitive technique for measuring two-photon absorption (TPA). An intensity-modulated femtosecond laser beam passes through a sample exhibiting TPA. A TPA signal at twice the modulation frequency is then generated and subsequent ...
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Journal ArticleJournal of Chemical Physics · June 23, 2002
The signal interference from turbulent spin dynamics in solution nuclear magnetic resonance spectroscopy was discussed. The unexpected dynamics, triggered by the joint action of the radiation damping and the distant dipolar field deteriorates the performan ...
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Journal ArticleOptics Letters · March 15, 2002
The phase and amplitude profile of a shaped pulse in the visible is transferred to a pulse in the near-infrared via an optical parametric amplification (OPA) process. Complex shaped pulses, such as multiple-pulse trains and pulses with high-order phase chi ...
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Journal ArticleJournal of Chemical Physics · February 1, 2002
The coupled-spin framework is used to take into account the properties of the "third-order experiments," namely Hahn echo decay and triple-quantum CRAZED. It is shown that the Hahn echo decay reflects the unique contrast present in other CRAZED experiments ...
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Journal ArticleIEEE Photonics Technology Letters · February 1, 2002
The frequency-domain differential phase-shift-keying (DPSK) using ultrafast laser pulses has been demonstrated. Spectral coding based on acoustic optical modulator pulse shaping is used for modulation, and the ultrafast pulse characterization based on spec ...
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Journal ArticlePacific Rim Conference on Lasers and Electro Optics CLEO Technical Digest · January 1, 2002
Direct and sensitive measurement of two-photon absorption (TPA) cross sections was presented. As a proof of principle, δ was measured for rhodamine 6G (R6G) in methanol. Results showed that the technique using moderate power from a mode-locked laser gave s ...
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Journal ArticleOptics Letters · November 15, 2001
We report the generation and amplification of ultrashort shaped pulses in the visible by a two-stage non-collinear optical parametric amplification process. Phase and amplitude profiles of the shaped pulses are conserved in our amplification scheme. The en ...
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Journal ArticleConference on Lasers and Electro Optics Europe Technical Digest · October 8, 2001
A double stage noncollinear optical parametric process was used to generate amplified shaped ultrashort pulses in the visible light range. The pulses were shaped in the spectral domain by the Acousto-optic modulation (AOM) technique. Pulse shapes were char ...
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Journal ArticleConference on Lasers and Electro Optics Europe Technical Digest · October 8, 2001
Feedback phase control of two optical pulses and its application for the optimization of acousto-optic pulse shaping was investigated. The difference between the reference pulse and target, provided feedback to the RF control signal and permitted closed lo ...
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Journal ArticleOptics Letters · March 15, 2001
We introduce a new variant of spectral interferometry, using spectrally dispersed ultrafast laser pulses and quadrature detection to measure optical thickness variations related to surface structure. We can resolve surface features with depths of 3 mm to 2 ...
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ConferenceOptics Infobase Conference Papers · January 1, 2001
Pulse spectral-domain differential-phase-shift-keying has been demonstrated using AOM-based pulse shaping for modulation and spectral interferometry for demodulation. The encoded differential phase is successfully retrieved despite of the nonlinear distort ...
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ConferenceOptics Infobase Conference Papers · January 1, 2001
Femtosecond laser pulse shaping and novel pulse shape detection methods can be used to develop Tb/s communications architectures, measure the onset of fiber nonlinearity, correct for distortions in optical amplifiers, and improve characterization of surfac ...
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Journal ArticleJournal of the Optical Society of America B Optical Physics · January 1, 2001
We demonstrate fast-frequency-hopping modulation that exploits the unique features of acousto-optic-modulator based laser pulse shaping and the spectrally and temporally resolved upconversion technique (STRUT) pulse-characterization method. These pulses ha ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 2001
We demonstrate a method for femtosecond, phase sensitive detection of optical polarization, using an acousto-optic pulse shaper to create a sequence of up to several hundred phase coherent pulses. Essential to this method is the ability of the acousto-opti ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 2001
By producing non-collinear optical amplification (NOPA) with an internal acousto-optic modulator (AOM), we generate amplified shaped ultrashort pulses (∼5μJ, <50fs) tunable from 500 to 700nm with up to 50THz bandwidths. The shaped pulses are fully characte ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · January 2001
The behavior of intermolecular multiple-quantum coherences in a variety of simple liquids with different chemical and magnetic properties is investigated experimentally and modeled by numerical simulations based on modified Bloch equations. The effects of ...
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Journal ArticleJournal of Optical Communications · January 1, 2001
Electro-optical data compression was demonstrated using the acousto-optic modulator (AOM) based ultrafast pulse shaping techniques. The comparison of electronic data packet into an optical data packet with effective data rate was demonstrated. The AOM-base ...
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Journal ArticleConference on Optical Fiber Communication Technical Digest Series · January 1, 2001
Pulse spectral-domain differential-phase-shift-keying has been demonstrated using AOM-based pulse shaping for modulation and spectral interferometry for demodulation. The encoded differential phase is successfully retrieved despite of the nonlinear distort ...
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Journal ArticlePacific Rim Conference on Lasers and Electro Optics CLEO Technical Digest · December 1, 2000
If quantum control and spectroscopy is to be applied in general to a wide range of atomic or molecular systems, methods should be developed to generate shaped optical pulses at widely tunable wavelengths to fit the corresponding resonance frequency of the ...
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Journal ArticleScience · October 6, 2000
We show experimentally and theoretically that two readily observed effects in solution nuclear magnetic resonance (NMR) - radiation damping and the dipolar field - combine to generate bizarre spin dynamics (including chaotic evolution) even with extraordin ...
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Journal ArticlePhysical review letters · October 2000
Resistive or hybrid magnets can achieve substantially higher fields than those available in superconducting magnets, but their spatial homogeneity and temporal stability are unacceptable for high-resolution NMR. We show that modern stabilization and shimmi ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · September 2000
A fast, efficient numerical algorithm is used to study intermolecular zero-quantum coherences (iZQCs) and double-quantum coherences (iDQCs) in two applications where the three-dimensional structure of the magnetization is important: high-resolution NMR in ...
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Journal ArticlePhysical Review Letters · July 24, 2000
The ability to engineer the interaction between a bath and a system is demonstrated. It is shown that this ability makes it possible to implement quantum error correction simply through dissipative dynamics, without requiring any external manipulation. An ...
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Journal ArticleMagnetic resonance imaging · June 2000
For the first time, we demonstrate here functional magnetic resonance imaging (fMRI) using intermolecular multiple-quantum coherences (iMQCs). iMQCs are normally not observed in liquid-state NMR because dipolar interactions between spins average to zero. I ...
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Journal ArticleJournal of Chemical Physics · March 15, 2000
In the weak-field limit, laser pulses optimized to induce vibrational wave packet recurrences in excited state potentials were calculated for Morse oscillators and for a real system [the X1Σ+ and A 3II(1) states of IBr]. Th ...
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Journal ArticleMagnetic Resonance in Medicine · 2000
The first intermolecular zero-quantum coherence (iZQC) MR images of the human brain at 4T are presented. To generate iZQC images, a modified echo- planar imaging pulse sequence was used which included an additional 45°RF pulse and a correlation gradient. T ...
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ConferenceOptics Infobase Conference Papers · January 1, 2000
We demonstrate a method for femtosecond, phase sensitive detection of optical polarization, using an acousto-optic pulse shaper to create a sequence of up to several hundred phase coherent pulses. Essential to this method is the ability of the acousto-opti ...
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ConferenceOptics Infobase Conference Papers · January 1, 2000
We demonstrate the generation of amplified (~ 8µJ) shaped ultrafast (< 50fs) pulses tunable from 500 to 700nm with bandwidths of up to 50THz. The characterisation of pulse phase and amplitude is provided. ...
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Journal ArticleConcepts in Magnetic Resonance · January 1, 2000
In the early 1990s, the traditional framework of NMR spectroscopy was challenged through a series of simple experiments. The pulse sequences used consisted of a few RF pulses and a few gradient pulses, and the samples were mixtures of simple molecules. The ...
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Journal ArticleOptics Letters · January 1, 2000
Ultrafast pulse shaping and ultrafast pulse spectral phase-retrieval techniques are used in the spectral interference measurement of nonlinear pulse propagation dynamics in dispersion-shifted optical fiber. Nonlinear responses in both amplitude profile and ...
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Journal ArticleJournal of Physical Chemistry A · December 9, 1999
This paper examines the parallels between magnetic resonance and optical spectroscopy, with the goal of determining to what extent the benefits of 2DNMR might be extended into the optical regime. Precise optical analogues of the simplest 2DNMR sequences (c ...
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Journal ArticleIEEE Photonics Technology Letters · December 1, 1999
We demonstrate real-time adaptive amplitude feedback in an AOM-based ultrafast optical pulse shaping system operating at λ = 1550 nm wavelength for optical communication applications. At the optimized feedback depth, a simple negative feedback algorithm co ...
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Journal ArticleJournal of Chemical Physics · October 8, 1999
NMR (nuclear magnetic resonance) nutation is treated with respect to demagnetizing-field effects on the evolution of spin coherences. A two-dimensional NMR nutation spectroscopy scheme is suggested consisting of a single radio frequency (RF) pulse and a fr ...
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Journal ArticleChemical Physics Letters · May 14, 1999
We propose and demonstrate an efficient numerical approach which switches back and forth between real and Fourier spaces to handle dipolar field effects for heterogeneous three-dimensional structures. Applications to magnetic resonance imaging and improvin ...
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Journal ArticleJournal of Chemical Physics · March 1, 1999
Calculations indicate that high vibrational states of oxygen and chlorine can be excited using a series of nonresonant Raman pulses, where both the pump and the Stokes pulses are chirped with linear frequency sweeps. Most of the previously reported coheren ...
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Journal ArticlePhysical Review A Atomic Molecular and Optical Physics · January 1, 1999
When coherent states of the electromagnetic field are used to drive the evolution of a quantum computer, a decoherence results due to the back reaction from the qubits onto the fields. We show how to calculate this effect. No assumptions about the environm ...
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Journal ArticleIQEC International Quantum Electronics Conference Proceedings · January 1, 1999
Shaped pulses are routinely used in various applications to alter the excitation dynamics of atoms and molecules. In this context, the interaction between intense, shaped ultrafast laser pulses and optically dense samples of Rb vapor was investigated. Exci ...
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Journal ArticlePhysical Review Letters · January 1, 1999
Ultrafast laser pulses with complex envelopes (amplitude and frequency modulated) are used to excite an optically dense column of rubidium vapor. Pulse reshaping, stimulated emission dynamics, and residual electronic excitation in the Rb vapor are all show ...
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Journal ArticleMolecular Physics · December 10, 1998
Scalar couplings have long been used to observe forbidden transitions indirectly, e.g., the multiple-quantum transitions detected frequently in the indirect dimension of multidimensional NMR experiments. Recent work has shown that intermolecular dipolar co ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 1998
Optical wavelength domain code-division multiplexing access (WD-CDMA) using an AOM-based ultrafast optical pulse shaping approach is proposed and demonstrated experimentally at 1550 nm. This new multiplexing technique utilizes wavelength domain codes that ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 1998
We summarize recent progress aimed at observing biochemical and biological dynamics using confocal microscopy with 3D spatial resolution down to a few hundred nm and temporal resolution to 15 fs. We also review recent control of population dynamics using t ...
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Journal ArticleOptics Letters · December 1, 1998
A fast, ultrafine-tunable delay line at 1550 nm is demonstrated by use of acousto-optic pulse shaping. Delays of up to 30 ps can be achieved without any optical readjustment. The delay is linear to the rf center frequency applied to the acousto-optic modul ...
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Journal ArticleOptics Express · November 1, 1998
We demonstrate high-resolution amplified pulse shaping using an acousto-optic modulator (AOM) at a center-wavelength of 795nm. The output pulses have energy of 200μJ/pulse and a transform-limited pulsewidth of 150fs. A spectral modulation of over 40 featur ...
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Journal ArticleChemical Physics Letters · July 10, 1998
We investigate the competition between intermolecular dipolar effects in multiple time intervals and develop a theoretical framework to understand coherence transfer when this competition is important. The quantum picture permits explicit evaluation of coh ...
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Journal ArticleScience (New York, N.Y.) · July 1998
A new method for magnetic resonance imaging (MRI) based on the detection of relatively strong signal from intermolecular zero-quantum coherences (iZQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; ...
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Journal ArticleMolecular Physics · February 1, 1998
Experimental investigations of the effects of moderately powerful (10–20 W cm-2) offresonant continuous lasers on NMR spectra provide no evidence for the B (3) field recently proposed, or for any other mechanism which depends on the l ...
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Journal ArticleJournal of Chemical Physics · January 22, 1998
Recent experimental work in two-dimensional solution NMR (nuclear magnetic resonance) has demonstrated anomalous cross-peaks and additional resonances due to dipolar couplings between distant nuclei. These spectra have been analyzed either classically, usi ...
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Journal ArticleJournal of Magnetic Resonance · January 1, 1998
Intermolecular zero-quantum coherences (iZQC) induced by the dipolar demagnetizing field can give both P- and N-type cross peaks. This paper shows that the relative intensities of the two types of iZQC peaks follow a simple relation, tan2 (θ/2), ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 1998
Quantum control is extended to complex molecular systems by using experimental feedback to control the acousto-optic tailoring of ultrashort pulses. ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 1998
Complex amplified pulses, including a 1 ps, 100 μJ tanh-swept sech pulse for adiabatic inversion, are generated experimentally. STRUT detection verifies the modulation and follows the dynamics induced by such pulses in Rb vapor. Applications to production ...
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Journal ArticleTechnical Digest European Quantum Electronics Conference · January 1, 1998
Quantum control involving multiple interactions with light of different colors within the same light pulse is analyzed. Experiments on I2 have demonstrated up to a 300% enhancement of the multiphoton yield with the appropriately chirped pulse. S ...
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Journal ArticleJournal of Lightwave Technology · December 1, 1997
We propose a novel scheme of differential phase shift keying (DPSK) in the optical frequency domain. We take advantage of the intrinsic coherence among spectral elements derived by spectrum slicing a femtosecond optical pulse, introducing differential phas ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · December 1, 1997
We discuss an architecture and underlying technologies of terabit-per-second network with the spectral-domain modulation. The baseline architecture is TDM which exploits our techniques for imposing > 1000 pixel phase and amplitude modulation on the spectru ...
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Journal ArticleChemical Physics Letters · November 28, 1997
Feedback quantum control, where the sample 'teaches' a computer-controlled arbitrary lightform generator to find the optimal light field, is experimentally demonstrated for a molecular system. Femtosecond pulses tailored by a computer-controlled acousto-op ...
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Journal ArticleJournal of magnetic resonance (San Diego, Calif. : 1997) · October 1997
A recently introduced density matrix picture for dipolar effects in solution NMR (1996, J. Chem. Phys. 105, 874) gave complete solutions for intermolecular multiple-quantum coherences for single-component samples without scalar couplings. This paper, for t ...
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Journal ArticleJournal of the Optical Society of America B Optical Physics · January 1, 1997
We focus theoretically and experimentally on the fundamental limitations of spectral pulse shaping using an acousto-optic modulator. We analyze the role of the relative thickness of the interaction region as dictated by the acousto-optic Q parameter and sh ...
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Journal ArticleJournal of Chemical Physics · July 15, 1996
Experimental observation of anomalous intermolecular cross-peaks in two-dimensional solution NMR spectra have attracted significant recent attention. Extremely simple pulse sequences on extremely simple samples with large equilibrium magnetization give res ...
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Journal ArticleScience (New York, N.Y.) · April 1996
Researchers interested in high-resolution nuclear magnetic resonance (NMR) spectroscopy have long sought higher magnetic fields to enhance resolution and simplify spectra. Magnets with substantially larger fields than those available in the best commercial ...
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Journal ArticleJournal of the American Chemical Society · January 1, 1996
Anomalous crosspeaks and additional resonances in the indirectly detected dimension have been previously observed in a number of 2D NMR experiments applied to samples having at least one concentrated species. These unexpected peaks exhibit all the characte ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 1996
High resolution (≈ 1000 pixels), rapidly updatable fs laser pulse shaping permits a terabit per second communications architecture and quantum control. ...
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Journal ArticleChemical Physics Letters · December 22, 1995
Numerous observations of anomalous intermolecular multiple-quantum and cross correlation peaks in solution NMR have led to a variety of theoretical treatments, some involving radiation damping or modified classical Bloch equations, others involving full qu ...
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Journal ArticleScience (New York, N.Y.) · February 1995
A magnetic resonance imaging technique based on intermolecular multiple-quantum coherences in solution (the correlated spectroscopy revamped by asymmetric z gradient echo detection or CRAZED experiment) is described here. Correlations between spins in diff ...
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Journal ArticlePhysical Review A · January 1, 1995
We show numerically that the complex hyperbolic secant pulse provides robust selective inversion of vibrational overtones. A density-matrix analysis is performed for a ten-level Morse-oscillator approximation of a diatomic molecule. We also show that in th ...
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ConferenceProceedings of SPIE the International Society for Optical Engineering · June 17, 1994
An absorption cell inside a Sagnac interferometer shapes laser pulses optimized to specific molecules, and a new acousto-optic pulse shaping technique provides improved flexibility for generating the complex waveforms needed for chemical applications. ...
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Journal ArticleOptics Letters · May 15, 1994
We demonstrate a new pulse-shaping technique, using an acousto-optic modulator as a spatial modulator in a zero-dispersion delay line. Compared with existing techniques, this approach simplifies optical alignment and dramatically improves update rates. It ...
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Journal ArticleJournal of Chemical Physics · January 1, 1994
We present detailed experimental and theoretical results on population transfer with frequency-swept picosecond laser pulses. Here, we demonstrate that intense frequency-swept pulses, when applied in the adiabatic limit, lead to both more efficient and mor ...
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Journal ArticlePhysical Review A · January 1, 1994
The effects of pulse shapes with simple phase and frequency modulation (phase proportional to amplitude or intensity, frequency proportional to intensity) are explored numerically. Many such shapes can be generated by combining self-phase-modulation with m ...
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Journal ArticleScience (New York, N.Y.) · December 1993
Intermolecular multiple-quantum coherences between bulk water and a glycoprotein fragment at modest concentration (20 mM) have been experimentally produced and detected, although such coherences are inconceivable in the normal theoretical framework of nucl ...
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Journal ArticleScience · January 1, 1993
Current experimental and theoretical progress toward the goal of controlling quantum dynamics is summarized. Two key developments have now revitalized the field. First, appropriate ultrafast laser pulse shaping capabilities have only recently become practi ...
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Journal ArticleJournal of Chemical Physics · January 1, 1993
It was recently reported that multiple-quantum NMR coherences could apparently be observed in water and other concentrated samples, in direct violation of established theory. These results were previously explained in a dressed-state framework as manifesta ...
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Journal ArticleSpringer Series in Chemical Physics · January 1, 1993
We demonstrate that picosecond frequency modulated laser pulses produce more efficient population transfer, and more selective excitation than equivalent (same spectral width) nearly transform limited laser pulses. We also note the ″ robustness″, or insens ...
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Journal ArticleJournal of Chemical Physics · January 1, 1993
We address the issue of localization of bond energy in a molecule by stopping intramolecular vibrational relaxation (IVR). We show through model calculations that appropriate frequency sweeps permit selective locking over a well-defined range of resonance ...
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Journal ArticleJournal of Magnetic Resonance 1969 · June 1, 1992
Shaped radiofrequency pulses are designed to extend the quadrupole-echo excitation bandwidth without insidious phase distortions. The quadrupole-shaped pulse (QUASH) is constructed by a simple iterative optimization procedure which directly solves a densit ...
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Journal ArticleScience (New York, N.Y.) · March 1992
Experimental studies show that optical irradiation far from any absorption bands can shift the resonances in a nuclear magnetic resonance (NMR) spectrum without significant heating. This effect may lead to increased dispersion in NMR studies of complex mol ...
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Journal ArticleJournal of Magnetic Resonance 1969 · January 1, 1992
Optimized waveforms for inverting pulses with areas up to 9π are reported. Both differences and similarities in rectangularity of inversion and sensitivity to inhomogeneity are found. For some applications many-π pulses may be more useful than low-flip-ang ...
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Journal ArticlePhysical Review Letters · January 1, 1992
We show experimentally, here for Na vapor, and theoretically that picosecond frequency-swept laser pulses create in multilevel systems an inversion profile that is far narrower than the pulse spectrum. This selectivity persists even when the Rabi frequency ...
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Journal ArticleJournal of Chemical Physics · January 1, 1992
The feasability of selective and complete population transfer between atomic or molecular levels by stimulated Raman scattering with delayed pulses involving spectrally broad light with characteristics typical for pulsed lasers is investigated. In extensio ...
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Journal ArticleConcepts in Magnetic Resonance · January 1, 1991
This is an overview of the effects of shaped radiofrequency pulses and instrumental requirements for pulse shaping. We summarize what is known in general about pulse shaping and the tradeoffs involved in choosing a pulse shape for specific experiments. We ...
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Journal ArticleJournal of Molecular Structure · January 1, 1990
A general discussion of quantum controllability leads to the specific focus of this work, namely the use of tailored radiation to excite rotational states, either specific |JM〉 states or superposition states which correspond to a high degree of molecular o ...
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Journal ArticlePhysical Review B · January 1, 1990
We report experimental characterization of a transient capacitative electrical effect in a GaAs photoconductive switch due to initial momentum relaxation of the carriers within the photoexcited plasma. The carrier-momentum-dampening rate (d) of approximate ...
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Journal ArticleJournal of Chemical Physics · January 1, 1990
In this paper we investigate the influence of optical density or superradiance on the photon echo decay using the coupled Maxwell-Bloch equations. Our theory applies to optically thick but dilute media, where the transition dipole-dipole interaction betwee ...
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Journal Articleundefined · December 1, 1989
A method has been developed for producing voltage-programmable, arbitrarily shaped laser pulses with approximately 100-fs resolution and >107-W peak power. Rectangular 600-1500-fs pulses have been used to probe hot carrier relaxation by photocon ...
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Journal Articleundefined · December 1, 1989
Laser pulses with finely controlled amplitude envelopes can selectively invert a portion of a Doppler broadened line, but the extent of inversion varies as the Rabi frequency of the transition changes. Modulation of the phase in addition to the amplitude c ...
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Journal ArticleConference on Lasers and Electro 0ptics · December 1, 1989
A method has been developed for producing voltage-programmable, arbitrarily shaped laser pulses with ~100-fs resolution and >107-W peak power. Rectangular 600-1500-fs pulses have been used to probe hot carrier relaxation by photoconductive sampl ...
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Journal ArticleJournal of Chemical Physics · January 1, 1989
We numerically investigate optical dephasing from as many as 500 interacting two-level absorbers by making the semiclassical approximation on the radiation-matter interaction which includes retarded dipole-dipole coupling and superradiant coupling. We calc ...
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Journal ArticleJournal of Chemical Physics · January 1, 1989
The time evolution of spins-1/2 subject to radiation damping, which is commonly encountered for solvent peaks at high field, is examined in detail. The well-known analytic results for rectangular pulses on undamped spin-1/2 systems are extended to the radi ...
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Journal ArticleApplied Physics Letters · December 1, 1988
We report a method for direct generation of voltage programmable, arbitrarily shaped laser pulses of subpicosecond duration and roughly 100 fs resolution. A waveguide intensity modulator was fabricated and incorporated into a fiber-grating pulse compressor ...
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Journal ArticleScience (New York, N.Y.) · November 1988
Pulsed excitation fields are routinely used in most laser and nuclear magnetic resonance (NMR) experiments. In the NMR case, constant amplitude (rectangular) pulses have traditionally been used; in laser spectroscopy the exact pulse shape is often unknown ...
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Journal ArticleJournal of Magnetic Resonance 1969 · February 15, 1988
The problem of predicting through numerical simulation the performance of pulse sequences applied to inhomogeneously broadened spin systems is examined. Numerical or analytical calculations of the dependence of magnetization on frequency do not lead immedi ...
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Journal ArticlePhysical Review A · January 1, 1988
Analytical and numerical calculations describe the effects of shaped radiation pulses on two-level systems in terms of quantum-mechanical scattering. Previous results obtained in the reduced case of amplitude modulation are extended to the general case of ...
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Journal ArticleRadiology · January 1988
Magnetic resonance images of the spine, chest, abdomen, and pelvis are commonly degraded by ghost artifacts. The authors have developed a new technique named FRODO (Flow and Respiratory artifact Obliteration with Directed Orthogonal pulses) to suppress the ...
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Journal ArticleJournal of Chemical Physics · January 1, 1988
We show that a fundamental assumption used in analyzing photon echo decays from interacting molecules - the assumption that the "pure" dephasing rate can be obtained by subtracting one half of the fluorescence decay rate (2T1)-1 from ...
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Journal ArticlePhysical Review A · January 1, 1988
We show that pulses of electromagnetic radiation with a hyperbolic-secant envelope and a hyperbolic-tangent frequency sweep are capable of exciting an inversion line shape in a collection of two-level absorbers that is highly insensitive to optical density ...
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Journal ArticleChemical Physics Letters · March 27, 1987
We show that the concept of phase-shifted laser pulse trains is meaningful only for purely amplitude-modulated pulses, and probably cannot be generalized to use the output of a normal pulsed laser. We demonstrate a laser system which gives picosecond pulse ...
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Journal ArticleChemical Physics Letters · January 9, 1987
Grafted "narrow reject" pulse shapes, whicch were shown previously to be capable of uniformly exciting a wide range of resonance frequencies with a sharp null directly on resonance for solvent suppression, are combined to generate multiple-pulse sequences. ...
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Journal ArticleOptics Letters · January 1, 1987
We demonstrate that fiber-optic compression can be sufficiently well characterized to permit generation of an arbitrarily shaped, l-psec-resolution laser pulse from a predistorted, much longer pulse. Coupled with our previously demonstrated capability to g ...
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Journal ArticleApplied Optics · January 1, 1987
We have produced complex software adjustable laser pulse shapes with ˜10-ps resolution, and pulse energies up to 100 μJ for spectroscopic applications. The key devices are a high damage threshold electrooptic directional coupler and a GaAs circuit for synt ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · January 1, 1987
We have shown theoretically and experimentally that specially shaped laser pulses can give enhanced excitation selectivity, compensate for experimental complications such as inhomogeneities and pulse amplitude jitter, and cleanly pump forbidden transitions ...
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Journal ArticleProceedings of SPIE the International Society for Optical Engineering · June 30, 1986
A theoretical model based on the laser rate equations is used to describe injection locking in pulsed dye lasers. It is shown that, in general, the frequency of the injection locked pulse is not equal to the frequency of the cw light-an unexpected result s ...
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Journal ArticleJournal of the Optical Society of America B Optical Physics · January 1, 1986
In molecular iodine, and most other gas-phase molecules as well, generation of a tt/2 or 7r pulse is theoretically impossible. This result can be understood by analogy with microwave spectroscopy, since the rotational contribution to the transition dipole ...
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Journal Articleundefined · December 1, 1985
Summary form only given. The authors present work with coherent and incoherent dual-frequency experiments designed to measure detailed microscopic collisional dynamics in molecular gases. In the incoherent version, a laser pulse sequence consisting of two ...
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Journal ArticlePhysical Review Letters · January 1, 1985
We have theoretically derived and experimentally demonstrated "narrow reject" pulses which give a uniform 2 excitation off resonance, and zero excitation in a sharp hole directly on resonance. They are also insensitive to relaxation effects. This shape is ...
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Journal ArticleJournal of Luminescence · January 1, 1984
Measurement of luminescence rather than polarization in coherent optical experiments allows more molecular information to be extracted. In this paper we discuss the advantages of this technique, such as frequency selectivity and time resolution, and applic ...
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Journal ArticleJournal of Magnetic Resonance 1969 · January 1, 1984
The multiple-quantum (MQ evolution of anisotropic spin systems with four to eight coupled protons is analyzed using a computer for the basic three-pulse sequence. MQ intensities are first investigated as a function of preparation time. The concept of time- ...
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Journal ArticleJournal of Magnetic Resonance 1969 · January 1, 1984
The effects of selective multiple-quantum pulse sequences have previously been analyzed by coherent averaging theory. However, convergence of the Magnus expansion used for those calculations is questionable in the experimentally important region of long cy ...
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Journal ArticleJournal of Chemical Physics · January 1, 1984
We present a new perturbation expansion for calculating the effects of arbitrary pulse shapes in two-level systems, even when the effects are grossly nonlinear. The first two terms have simple physical interpretations. This expansion converges rapidly for ...
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Journal ArticleChemical Physics Letters · 1983
We report115 In nuclear relaxation rates for molten InCl2 and visible-near-infrared absorption spectra for molten InCl2 and In2Cl3. A weak band at 2.1 eV in InCl2 is attributed to the intervalence transfer excitation In+ →- In3+. The intensity of the inter ...
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Journal ArticleJournal of Chemical Physics · January 1, 1983
In this paper we present novel and simple pulse sequences for enhancing the intensity of forbidden or highly nonresonant optical transitions. These sequences provide a straightforward approach to circumventing the most serious limitation of optical coheren ...
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Journal ArticleJournal of Chemical Physics · January 1, 1983
The effects of intense laser pulse trains in coupled multilevel systems (such as pure or mixed molecular crystals) are analyzed by calculating exact density matrix evolutions. It is shown that two-level approximations are inadequate. The contributions of e ...
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Journal ArticleJournal of Chemical Physics · January 1, 1983
In this series of papers we report on the generation and application of multiple pulse phase coherent sequences in optical spectroscopy. In this paper the effects of intense pulse trains on systems with only two resonant energy levels are analyzed, with pa ...
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Journal ArticleChemical Physics Letters · May 14, 1982
A sixteen pulse sequence which excites only four-quantum transitions in multiple-quantum NMR is shown to give good selectivity on two molecules, benzene and n-butyl bromide. The behavior as pulse sequence parameters are varied is shown to be consistent wit ...
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Journal ArticleJournal of Physical Chemistry · January 1, 1982
This paper addresses questions important to the origin of optical dephasing and vibrational energy redistributions in molecules. Several laser techniques are discussed and three major findings are presented. These findings are related to (a) optical dephas ...
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Journal ArticleJournal of the American Chemical Society · January 1, 1981
The NMR of oriented molecules gives detailed structural information, but isotopic substitution is often required for analysis. An alternative to synthesizing labeled molecules is to observe multiple-quantum spectra. Symmetry arguments show that multiple-qu ...
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Journal ArticleJournal of Chemical Physics · January 1, 1981
Irradiating a spin system with an appropriate sequence of phase shifted pulses excites only certain orders of multiple-quantum transitions. Using such sequences in preparation and detection produces a large signal/noise enhancement for the multiple-quantum ...
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Journal ArticleJournal of Chemical Physics · January 1, 1980
The question of whether a molecule can be made to absorb and emit photons only in groups of n is treated. Pulse sequences are introduced which in effect selectively induce the absorption of only groups of n photons. This causes only n-quantum transitions e ...
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Journal ArticlePhysical Review Letters · January 1, 1979
Wideband selective n-quantum excitation in the NMR of coupled spins is demonstrated for the first time. By a combination of multiple pulse averaging and phase shifts a pure n-quantum excitation operator can be produced (n=2). This allows enhancement of nor ...
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Journal ArticleInfrared Physics · 1968
Results of a computer analysis of the basic designs are given relating their characteristics with their construction and film properties. Data on performance of germanium, silicon monoxide filters are given with environmental conditions and time. The perfo ...
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