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Title:Ultrafast studies of diffusion and electron transfer
Author(s):Miers, Jeffrey Britt
Doctoral Committee Chair(s):Dlott, Dana D.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Physical
Biophysics, General
Abstract:Picosecond flash photolysis is used to study the recombination of carbon monoxide to protoheme in glycerol:water over ten decades in time (1 ps to 10 ms). The rebinding consists of an initial nonexponential geminate phase followed by a slower exponential bimolecular phase. The entire time course of this reaction between 260 and 300 K can be explained in a unified way using a simple, analytically tractable diffusion model involving just three parameters: the relative diffusion constant, the contact radius, and the intrinsic rate of reaction at contact.
Fiber-optic pulse compression of the picosecond laser is used to increase the temporal resolution of the apparatus from 2 ps to 250 fs. The femtosecond pulses are subsequently used to observe back electron transfer in pyrylium borate ( (Py$\sp+$) (Ar$\sb4$B$\sp-$)) ion pairs in benzene. Substituent groups on the borate are varied in a systematic way to change the driving force, $\Delta{\rm G}\sb{\rm bet}$, of the back transfer reaction. Back transfer rates between 6.3 $\times$ 10$\sp{10}$ and 2.6 $\times$ 10$\sp{11}$ s$\sp{-1}$ are observed. Plots of k$\sb{\rm bet}$ vs. $\Delta{\rm G}\sb{\rm bet}$ show a Marcus inverted region. The forward and back rates are not equal because different molecular orbitals are involved depending on the direction of transfer.
The research in this thesis was supported by the National Science Foundation through grants NSF DMR 87-21243 and NSF DMR 91-04130. Some of the equipment used in this work was partially supported by the US Army Research Office through grant DAALO3-90-G-0030. The author acknowledges support from a Molecular Biophysics Traineeship on Public Health Service Grant GM08276 and, during the preparation of this thesis, by the MFEL program through the Office of Naval Research contract N00014-91-C-0170.
Issue Date:1992
Rights Information:Copyright 1992 Miers, Jeffrey Britt
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9236542
OCLC Identifier:(UMI)AAI9236542

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