Degree Type

Thesis

Date of Award

2008

Degree Name

Master of Science

Department

Chemistry

First Advisor

Hans U. Stauffer

Second Advisor

Jacob Petrich

Third Advisor

Victor Lin

Abstract

The subpicosecond time evolution of a push-pull stilbene, 4-dimethylamino-4'-nitrostilbene (DANS) following 400 nm excitation in acetonitrile is observed with vibrational resolution using the recently-developed fs/ps CARS probe technique. Raman-active modes in the fingerprint region of the vibrational spectrum are observed to evolve, both in intensity and in frequency. The evolution of the DANS vibrational spectrum in the nitro symmetric stretch region is probed, exhibiting a frequency upshift on a 300 fs timescale. These findings agree well with timescales observed in transient absorption/gain experiments and support the formation of an intramolecular charge transfer (ICT) state on a subpicosecond timescale in acetonitrile that precedes the fast (∼12 ps) internal conversion timescale observed in prior studies. Simulations of fs/ps CARS technique help in understanding the experimental transition from time resolved CARS to fs/ps CARS. Simulations indicate an increase in frequency resolution of modes as well as direct measurement of the vibrational modes.

DOI

https://doi.org/10.31274/rtd-180813-16424

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Beth Marie Prince

Language

en

Proquest ID

AAI1453106

OCLC Number

237183438

ISBN

9780549541769

File Format

application/pdf

File Size

53 pages

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