The degree of charge transfer in ground and charge-separated states revealed by ultrafast visible pump/mid-IR probe spectroscopy.

Journal Article (Journal Article)

We demonstrate a new femtosecond visible pump/mid-IR probe spectroscopic approach to assess directly the ground- and excited-state degrees of charge transfer (CT) in donor-spacer-acceptor (D-Sp-A) structures. Two classes of (porphinato)zinc(II) (PZn)-based D-Sp-A compounds with either quinonyl (Q) or N-(N'-octyl)pyromellitic diimide (PI) electron acceptors were interrogated. Carbonyl antisymmetric stretching mode frequency domain transient-IR spectra of these species were recorded and analyzed for the Q/PI moieties. These data show that the acceptor mode frequency shift, DeltanuA, determined by this method provides a more accurate measure of the degree of CT in ground and charge-separated states relative to other techniques which rely on the ground-state frequency shift alone. This approach enables determination of new experimental benchmarks to test the power of complimentary computational methods and provides a means to probe the degree of CT in transitions that either overlap strongly with other bands or possess low oscillator strength.

Full Text

Duke Authors

Cited Authors

  • Rubtsov, IV; Kang, YK; Redmore, NP; Allen, RM; Zheng, J; Beratan, DN; Therien, MJ

Published Date

  • April 2004

Published In

Volume / Issue

  • 126 / 16

Start / End Page

  • 5022 - 5023

PubMed ID

  • 15099057

Electronic International Standard Serial Number (EISSN)

  • 1520-5126

International Standard Serial Number (ISSN)

  • 0002-7863

Digital Object Identifier (DOI)

  • 10.1021/ja030674k

Language

  • eng