Temperature-dependent (10-240 K) relaxation of vibrational excitons in KClO4 crystal

Year: 1989

Authors: Righini R., Angeloni L., Foggi P., Castellucci E., Califano S.

Autors Affiliation: Dipartimento di Chimica, Università di Firenze, 50121 Florence, Italy

Abstract: The relaxation times of vibrational excitons in KClO4 have been measured between 10 and 240 K by picosecond time-resolved CARS spectroscopy. The low temperature data are consistent with energy decay mechanisms based on three-phonon scattering processes. At higher temperature the linewidth of the symmetric stretching ?1 has a well defined linear dependence on T, showing that three-phonon scattering is still the main relaxation mechanism. In contrast, the ?2 bending mode has a marked T2 dependence, showing that four-phonon and higher-order depopulation and dephasing mechanisms control the overall relaxation rate. Finally, the strong temperature dependence of the linewidth of the 2?2 overtone is interpreted in terms of the relaxation of an undispersed, quasi-free two-phonon state.

Journal/Review: CHEMICAL PHYSICS

Volume: 131 (2-3)      Pages from: 463  to: 472

KeyWords: potassium perchlorate
DOI: 10.1016/0301-0104(89)80191-0

Citations: 17
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