Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9575384 | Chemical Physics | 2005 | 7 Pages |
Abstract
The S1-S0 fluorescence excitation and dispersed fluorescence spectra of 2- and 1-methylanthracene are measured in a supersonic free jet expansion. The barrier heights to internal rotation in the S0 and S1 states of 2-methylanthracene are determined to be 69 and 335 cmâ1, respectively, by using a one-dimensional free-rotor model. A prominent 0-0 transition has been observed in the fluorescence excitation spectrum of 1-methylanthracene, but no methyl rotational bands have been detected in both the excitation and dispersed fluorescence spectra. The potential energy curves of the methyl rotation are obtained for 2- and 1-methylanthracene with density functional theory (DFT) calculations and time-dependent (TD)-DFT calculations at the B3LYP/6-31 + G(d,p) level. The barrier heights and the phase of the potential energy curve are very different between 2- and 1-methylanthracene and substantially depend on the electronic state. These differences are consistently explained by a Ï*âÏ* hyperconjugation effect introduced by Nakai and Kawai [Chem. Phys. Lett. 307 (1999) 272].
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Masayuki Nakagaki, Eriko Nishi, Kenji Sakota, Kaori Nishi, Haruyuki Nakano, Hiroshi Sekiya,