Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The semiconductor photoinduced valence isomerizations of several strained saturated hydrocarbons were investigated. Particularly, the radical cation rearrangements of quadricyclane and bishomocubane on ZnO and CdS were explored with respect to various experimental conditions; solvent, light intensity, temperature and presence of oxygen. A kinetic treatment of the data obtained revealed that bimolecular processes at the surface may occur by two routes: reaction between two adsorbed species, the Langmuir-Hinshelwood model and reaction of an adsorbed molecule with a molecule in solution, an Eley-Rideal type process. Unimolecular reaction at the surface was adequately described by only considering adsorbed substances. The square root relationship between that of rate of reaction and light intensity was attributed to significant recombination of the electron-hole pairs within the bulk of the semiconductor. The valence isomerization of quadricyclane on CdS was observed in the absence of light. The thermal reaction was thought to be an electron transfer rearrangement and may have been a result of trapped holes at the surface, lying above the valence band.;A series of related strained hydrocarbons; quadricyclane, tetracyclo({dollar}\sp{lcub}2,8{rcub}{dollar}.0{dollar}\sp{lcub}4,6{rcub}{dollar}) octane, pentacyclo(4.3.0.{dollar}\sp{lcub}2,4{rcub}{dollar}.0{dollar}\sp{lcub}3,8{rcub}{dollar}.0{dollar}\sp{lcub}5,7{rcub}{dollar}) nonane and pentacyclo({dollar}\sp{lcub}2,4{rcub}{dollar}.0{dollar}\sp{lcub}3,8{rcub}{dollar}.0{dollar}\sp{lcub}5,7{rcub}{dollar}) decane were examined as to their radical cation rearrangements or lack thereof on illuminated CdS, ZnO and sensitized by dicyanoanthracene. The reactivity of these compounds was investigated by molecular mechanics (MM2) and semiempirical (MNDO) calculations. The results of which suggested that the activation energy of the radical cation isomerizations varied considerably and was attributed to the differences in the structure of the radical cations.



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