Nieman, George Carroll (1965) Triplet exciton phenomena in benzene crystals. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-04172003-162535
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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.))|
|Degree Grantor:||California Institute of Technology|
|Division:||Chemistry and Chemical Engineering|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||7 August 1964|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||18 Apr 2003|
|Last Modified:||26 Dec 2012 02:37|
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