Detection Of Intramolecular Charge Transfer And Dynamic Solvation In Eosin B By Femtosecond Two-dimensional Electronic Spectroscopy

Ghosh, Soumen

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https://hdl.handle.net/2142/51182 Copy

Description

Title

Detection Of Intramolecular Charge Transfer And Dynamic Solvation In Eosin B By Femtosecond Two-dimensional Electronic Spectroscopy

Author(s)

Ghosh, Soumen

Contributor(s)

• Beck, Warren F.
• Roscioli, Jerome D.

Issue Date

2014-06-17

Keyword(s)

Mini-symposium: Spectroscopy in Kinetics and Dynamics

Abstract

We have employed 2D electronic photon echo spectroscopy to study intramolecular charge-transfer dynamics in eosin B. After preparation of the first excited singlet state (S$_1$) with 40-fs excitation pulses at 520 nm, the nitro group (--NO$_2$) in eosin B undergoes excited state torsional motion towards a twisted intramolecular charge transfer (TICT) state. As the viscosity of the surrounding solvent increases, the charge-transfer rate decreases because the twisting of the --NO$_2$ group is hindered. These conclusions are supported by the time evolution of the 2D spectrum, which provides a direct measure of the the ground-to-excited-state energy gap time-correlation function, $M(t)$. In comparison to the inertial and diffusive solvation time scales exhibited by eosin Y, which lacks the nitro group, the $M(t)$ function for eosin B exhibits under the same conditions an additional component on the 150-fs timescale that arises from quenching of the S$_1$ state by crossing to the TICT state. These results indicate that 2D electronic spectroscopy can be used as a sensitive probe of the rate of charge transfer in a molecular system and of the coupling to the motions of the surrounding solvent. (Supported by grant DE-SC0010847 from the Department of Energy, Office of Basic Energy Sciences, Photosynthetic Systems program.)

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/51182

DOI

https://doi.org/10.15278/isms.2014.TH03

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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