Composite and shaped pulses for efficient and robust pumping of disconnected eigenstates in magnetic resonance.

Published

Journal Article

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 hyperpolarization in seconds. Significant lifetime enhancements have been found with "disconnected eigenstates" such as the singlet state between a pair of nearly equivalent spins, or the "singlet-singlet" state involving two pairs of chemically equivalent spins; the challenge is to populate these states (for example, from thermal equilibrium magnetization or hyperpolarization) and to later recall the population into observable signal. Existing methods for populating these states are limited by either excess energy dissipation or high sensitivity to inhomogeneities. Here we overcome the limitations by extending recent work using continuous-wave irradiation to include composite and adiabatic pulse excitations. Traditional composite and adiabatic pulses fail completely in this problem because the interactions driving the transitions are fundamentally different, but the new shapes we introduce can move population between accessible and disconnected eigenstates over a wide range of radio-frequency (RF) amplitudes and offsets while depositing insignificant amounts of power.

Full Text

Duke Authors

Cited Authors

  • Theis, T; Feng, Y; Wu, T; Warren, WS

Published Date

  • January 2014

Published In

Volume / Issue

  • 140 / 1

Start / End Page

  • 014201 -

PubMed ID

  • 24410222

Pubmed Central ID

  • 24410222

Electronic International Standard Serial Number (EISSN)

  • 1089-7690

International Standard Serial Number (ISSN)

  • 0021-9606

Digital Object Identifier (DOI)

  • 10.1063/1.4851337

Language

  • eng