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VOLUME 58 (1993) | ISSUE 11 |
PAGE 874
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Destruction of the vibrational structure of the band of instantaneous fluorescence spectra of polar solutions with increasing delay time
Pavlovich V. S. , Zablotskii S. V.
The evolution of the instantaneous flurorescence spectra of polar compounds in alcohols has been studied at delay times t greater than the average lifetime in the excited state by a factor of 5, 6, or more. As t is increased, one observes a destruction of the vibrational structure, a coalescence of the less intense vibrational bands, and a compression of the spectrum. This compression then gives way to an expansion, and the structure is partially restored. It is suggested that the effects observed stem from nonadiabatic random perturbations of an excited molecule which result from an abrupt reorientation of the molecules of the medium and their polar fragments (OH groups) and from a reorientation of the fragments of the compounds themselves. Such perturbations modulate the phase and amplitude of the radiation and also alter the frequency, leading to a spectral "borrowing" and a redistribution of intensity in the electronic-vibrational emission spectrum.
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