Quantum chemical and vibronic analysis of the 1thinsp;2B2harr;1thinsp;2A2, 2thinsp;2B2transition in benzylhyphen;h7and benzylhyphen;d7radicals

摘要

The QCFF/PI+CI method and the CNDO/S+CI method in the floating atomic orbital basis set are used to study vibronic structure of the 1thinsp;2B2harr;1thinsp;2A2, 2thinsp;2B2transition in benzylhyphen;h7and benzylhyphen;d7radicals, arising from the activity ofa1andb1inhyphen;plane modes. It is shown that the 6a10line has its intensity almost entirely due to the borrowing from the 1thinsp;2A2rarr;1thinsp;2A2transition via the 1thinsp;2A2ndash;1thinsp;2A2coupling. We demonstrate tha the 1thinsp;2A2and 2thinsp;2B2states are strongly mixed by ngr;8band ngr;6bmodes. The unperturbed 1thinsp;2A2state lies sim;850 cmminus;1below the unperturbed 2thinsp;2B2state. The coupling depresses strongly the position of the 6b10level mixing it markedly with the level arising from Cndash;CH2rock (ngr;18bin other assignments) fundamental. Threehyphen;mode vibronic analysis of the absorption and emission spectrum produces vibronic structure that agrees well with the observed spectra. The adiabatic frequency of the ngr;14(b1) mode in the 1thinsp;2B2state is shown to be depressed markedly by vibronically induced mode mixing with ngr;8bmode due to the 1thinsp;2B2ndash;nthinsp;2A2interactions.