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|Title:||High Pressure Optical and Photoelectrical Studies|
|Author(s):||Littman, Jon Eric|
|Department / Program:||Chemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The effect of high pressures to 40 kilobars and temperatures down to 100(DEGREES)K on the intensity and lifetime of NaCl:Tl('+) and NaCl:In('+) has been studied. A kinetic model describing these phosphors has been presented. The excited ('3)T(,lu) state is radiatively and nonradiatively coupled to the ground state, ('3)A(,lg). The radiative rate increases with increasing pressure due to an increase of the spin orbit coupling. The nonradiative rate is not pressure sensitive. The ('3)T(,lu) state is in thermal equilibrium with the ('3)A(,lu) level below it. For NaCl:Tl('+) the energy separating the minima of the ('3)T(,lu) and ('3)A(,lu) was found to be 22.7 meV and was too small to be measured for NaCl:In. Pressure did not effect the thermal energy difference. It was found that the nonradiative rate, k(,nrT), increased with decreasing temperature decreasing the quantum yield.
The effect of pressure to 10 kilobars at 300 K on the relative flatband potential of n and p type InP in aqueous 2Te('2-)/Te(,2)('2-) and V('+2)/V('+3) electrolytes respectively was studied. This work presents a novel way to measure experimentally the effect of pressure on the bottom of the conduction band and the top of the valence band independently of one another. It was determined that the increases of the energy gap of the direct transition of InP, 8.5 meV/kbar, is to first order due to the movement of the conduction band.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.
|Date Available in IDEALS:||2014-12-15|