Photophysical Studies: I. Singlet Quenching in Naphthalene-Conjugated Diene Bichromophores. II. Flourescence of Aromatic Hydrocarbon-Tertiary Amine Bichromophores. III. Intersystem Crossing in the Methyl Benzenes

• Main Author: Quina, Frank Herbert
• Format: Others
• Language: en
• Published: 1973
• Online Access: https://thesis.library.caltech.edu/11130/1/Quina_fh_1973.pdf; Quina, Frank Herbert (1973) Photophysical Studies: I. Singlet Quenching in Naphthalene-Conjugated Diene Bichromophores. II. Flourescence of Aromatic Hydrocarbon-Tertiary Amine Bichromophores. III. Intersystem Crossing in the Methyl Benzenes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/zq65-sd49. https://resolver.caltech.edu/CaltechTHESIS:07202018-143432826 <https://resolver.caltech.edu/CaltechTHESIS:07202018-143432826>

<p>Part I describes the synthesis, photochemistry, and fluorescence of several naphthalene-conjugated diene bichromophores. The data for these systems and for suitable reference systems are used to discuss and develop models for the bimolecular singlet quenching phenomenon.</p> <p>Part II describes the synthesis and fluorescence of several aromatic hydrocarbon-tertiary amine bichromophores. The fluorescence properties of these systems are related to the accessibility of various conformations and possible configurational requirements of amine singlet quenching are discussed.</p> <p>Part III reports the results of a systematic study of intersystem crossing in the methyl benzenes. Along with measured singlet lifetimes and literature values for the fluorescence quantum yields, these data allow evaluation of the rate constants for deactivation of the first excited singlet state of the methyl benzenes in degassed cyclohaxane solution. A qualitative dependence of the intersystem crossing rates on the sym­metry of methyl substitution is found and mechanisms involving inter­system crossing to the second triplet state are proposed to account for this result. Non-radiative decay of the first excite singlet state via pathways other than fluorescence and intersystem crossing is found to be a significant process for all of the methyl benzenes except p-xylene.</p>