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Triplet Exciton phenomena in Benzene Crystals


Nieman, George Carroll (1965) Triplet Exciton phenomena in Benzene Crystals. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/FR70-V452.


NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Various aspects of the triplet exciton problem are investigated. By studying three-component isotopic mixed crystals of benzene it is shown that trap-to-trap triplet excitation migration is very rapid compared to singlet excitation migration. The closely related phenomenon of triplet-triplet annihilation is also discussed. Triplet-triplet annihilation accounts for the production of delayed fluorescence in molecular crystals and for the quenching of all phosphorescence from pure crystals of n-electron molecules. By studying the small quasiresonance shifts introduced in the C[subscript 6]H[subscript 6] phosphorescence by changing the degree of deuteration of the benzene host crystal, the nearest neighbor "pairwise" triplet exciton matrix element ([beta]) for benzene is determined to be 12[...]1 cm[superscript -1]. This compares very well with the rough value of 9 cm[superscript -1] determined from excitation transfer studies and is only slightly less than that (18 cm[superscript -1] found for the singlet exciton interaction. These investigations also imply a new interpretation of the factor group splitting of the first singlet-singlet transition in crystalline benzene. Optical evidence is presented which shows that benzene in its lowest triplet state is not a regular hexagon. Rather detailed phosphorescence spectra of various deuterated benzenes are also presented.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:(Chemistry)
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Robinson, G. Wilse
Thesis Committee:
  • Unknown, Unknown
Defense Date:7 August 1964
Record Number:CaltechETD:etd-04172003-162535
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1404
Deposited By: Imported from ETD-db
Deposited On:18 Apr 2003
Last Modified:09 Feb 2024 18:21

Thesis Files

PDF (Nieman_gc_1965.pdf) - Final Version
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