Picosecond laser studies of V-T processes in gases and electronic excitation transport in disordered systems

Thumbnail Image
Date
1987
Authors
Hedstrom, John
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Organizational Unit
Journal Issue
Is Version Of
Versions
Series
Department
Chemistry
Abstract

SVL fluorescence spectroscopy was used to study intra- molecular energy transfer from the 0(DEGREES) level of aniline induced by collisions with CO(,2). The populations of eight aniline vibronic growth levels, as a function of CO(,2) pressure, were monitored. Collision gas pressures were adjusted to keep aniline-CO(,2) interactions within the single-collision regime. To first order, collision-induced energy transfer from the 0(DEGREES) level of aniline for CO(,2) as the collision gas follows the same flow pattern as was found in previous studies when Ar, H(,2)O or CH(,3)F were the collision partners('1,2);Time-correlated photon counting was used to measure concen- tration dependent fluorescence depolarization for rhodamine 6G in glycerol. Fluorescence decays from these viscous solutions provide data for analyzing the three-dimensional, three-body excitation transport theory developed by Gochanour, Andersen and Fayer for disordered systems('3). Solution concentrations of rhodamine 6G range from 1.7 x 10('-4) to 2.4 x 10('-3) M. Differences between optimized theoretical and experimental profiles are shown to be dominated by experimental artifacts arising from excitation trapping by rhodamine 6G aggregates and from self-absorption in solution cells thicker than 10 (mu)m;The two-dimensional, two-body excitation theory developed by Loring and Fayer('4) was also examined using time-resolved fluores- cence depolarization techniques. The samples, made up of sub- monolayers of rhodamine 3B adsorbed onto optically flat fused silica yield fluorescence profiles which agree well with profiles developed from the theory for reduced surface coverages up to (TURN)0.4. At higher coverages, excitation trapping by rhodamine 3B aggregates;truncates the depolarization process, yielding apparent reduced coverages which are appreciably lower than the true coverages; ('1,2,3,4)Please see dissertation for references.

Comments
Description
Keywords
Citation
Source
Subject Categories
Copyright
Thu Jan 01 00:00:00 UTC 1987