Date of Award

6-1976

Document Type

Union College Only

Degree Name

Bachelor of Science

Department

Chemistry

Language

English

Abstract

Nonradiative processes cause the fluorescence quantum yield to be less than one. Elucidation of nonradiative decay mechanisms without knowing the location of triplet states is difficult. Determination of the fluorescence quantum yield (Øf) as a function of temperature can provide valuable information about relative location of triplet states and the nonradiative processes which result from having a triplet near the energy of the first excited singlet state. Methyl-2-anthroate is very sensitive to solvent polarity. The Øf values and S1 energies vary greatly, depending on the solvent environment. Temperature studies on Øf have indicated the intersystem crossing (ISC) to a nearby triplet is probably the major mechanism for non-radiative decay in aprotic solvents. The data in polar hydrogen bonding solvents indicate that internal conversion and/ or intersystem crossing to T1 may result in nonradiative decay in protic solvents. Activation energies obtained from Arrhenius plots of the ISC process in various aprotic solvents indicate that a common low frequency vibrational mode of 111 cm-1 may be responsible for coupling with the nearby triplet.

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