Solvent exchange in excited-state relaxation in mixed solvents

Koti, A. S. R. ; Periasamy, N. (2000) Solvent exchange in excited-state relaxation in mixed solvents Journal of Fluorescence, 10 (2). p. 177. ISSN 1053-0509

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Official URL: http://www.springerlink.com/content/g08p29015jpj05...

Related URL: http://dx.doi.org/10.1023/A:1009451327695

Abstract

The fluorescence of styrylthiazoloquinoxaline (STQ) in the solvent mixture methanol and dichloromethane (DCM) and 2-octanol have many common characteristics: biexponential fluorescence decay, wavelength-dependent amplitudes, a negative amplitude for the short-lifetime component at long emission wavelengths, and a time-dependent red shift of the emission spectrum. In octanol, the fluorescence lifetime decreases with increasing temperature, whereas the lifetime increases with temperature in the methanol/DCM mixture. The fluorescence characteristics in 2-octanol (η=7.29 cP) are readily explained by the conventional model of excited-state relaxation kinetics by solvent reorientation. This model is not applicable for low-viscosity (η=0.455 cP) solvent mixtures. A model of excited-state relaxation kinetics involving solvent exchange (versus solvent reorientation in pure solvents) in the excited state is proposed for the solvent mixture. The model assumes that the solvent compositions around the solute are different in the ground and excited states and the solvent composition is temperature dependent.

Item Type:Article
Source:Copyright of this article belongs to Springer.
Keywords:Fluorescence Spectroscopy; Lifetimes; Methanol; Dichloromethane
ID Code:37337
Deposited On:22 Apr 2011 12:31
Last Modified:17 May 2016 20:15

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