Original scientific paper

The Vibrational Stark Effect on the Doubly Degenerate ν₁₉ Modes of the Benzene Guest Molecules in Hofmann Type Clathrates

Ljupčo Pejov ; Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Cyril and Methodius University, P. O. Box. 162, 91001 Skopje, Macedonia
Liljana Andreeva ; Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Cyril and Methodius University, P. O. Box. 162, 91001 Skopje, Macedonia
Biljana Minčeva-Sukarova ; Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Cyril and Methodius University, P. O. Box. 162, 91001 Skopje, Macedonia
Vladimir M. Petruševski ; Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Cyril and Methodius University, P. O. Box. 162, 91001 Skopje, Macedonia

Abstract

An alternative mechanism is proposed for the observed splitting of the ν₁₉ γ(CH) mode of the benzene guest molecules in Hofmann type clathrates to the one presented previously.1 According to the proposed model, the splitting is due to the vibrational Stark effect. A simple quantum theoretical model for this effect is derived, based on the degenerate-case stationary perturbation theory, both with and without explicit inclusion of the vibrational angular momentum. The model allows estimation of the relative field strengths at the enclathration sites of the guest molecules in a series of structurally similar clathrates. The derived equations may be used for calculation of the local field strength as well, if particular anharmonic coupling constants for enclathrated species are available. The predictions of the proposed method are fully in line with the observed room temperature-low temperature trends for a particular clathrate, as well as with the trends in the series of isostructural clathrate compounds for which experimental data are available.

Keywords

vibrational Stark effect; Hofmann clathrates; host-guest interactions; electrostatic field induced degenerate mode splitting; perturbation theory

Hrčak ID:

131997

URI

https://hrcak.srce.hr/131997

Publication date:

4.12.2000.

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