| Autor: |
Montoro, Teresa, Chabbert, Marie, Tyrzyk, Janusz, Lami, Hans |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 9/1/1988, Vol. 89 Issue 5, p2712, 8p |
| Abstrakt: |
Subnanosecond-time-resolved fluorescence spectra of 1-methylindole and 2,3-dimethylindole in n-butanol were recorded at temperatures of 118–293 K in order to elucidate the unusually large Stokes shift of indoles in polar solvents. Above 200 K the presence of an isoemissive point in the emission spectra indicates interconversion between a partially relaxed excited state (B* state) and a completely relaxed one (R* state). The B*→R* process is characterized by a rate parameter identical with the inverse of the longest longitudinal dielectric relaxation time of the solvent and thus due to the collective reaction of butanol tetramers far removed from the solute. Analysis of the time evolution of the spectral shift below 200 K, reveals that the B* emission spectrum undergoes a Bakhshiev-type continuous red shift characterized by a relaxation time which compares well with the Debye relaxation time of the second dielectric dispersion region and may therefore be attributed to the rotation of a butanol monomer close to the solute molecule. As concerns the nature of the emitting states, neither the 1Lb–1La level inversion interpretation nor the 1La/CT (1La state with increased charge–transfer character) interpretation is wholly consistent with the results of this investigation. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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