標題: The Role of the n pi* (1)A(u) State in the Photoabsorption and Relaxation of Pyrazine
作者: Lin, Chih-Kai
Niu, Yingli
Zhu, Chaoyuan
Shuai, Zhigang
Lin, Sheng Hsien
Department of Applied Chemistry
關鍵字: absorption;pyrazines;quantum chemistry;excited states;vibronic coupling
公開日期: 4-Nov-2011
摘要: The geometric, energetic, and spectroscopic properties of the ground state and the lowest four singlet excited states of pyrazine have been studied by using DFT/TD-DFT, CASSCF, CASPT2, and related quantum chemical calculations. The second singlet n pi* state, (1)A(u), which is conventionally regarded dark due to the dipole-forbidden (1)A(u) <- (1)A(g) transition, has been investigated in detail. Our new simulation has shown that the state could be visible in the absorption spectrum by intensity borrowing from neighboring n pi* (1)B(3u) and pi pi* (1)B(2u) states through vibronic coupling. The scans on potential-energy surfaces further indicated that the (1)A(u) state intersects with the (1)B(2u) states near the equilibrium of the latter, thus implying its participation in the ultrafast relaxation process.
URI: http://dx.doi.org/10.1002/asia.201100472
ISSN: 1861-4728
DOI: 10.1002/asia.201100472
Volume: 6
Issue: 11
起始頁: 2977
結束頁: 2985
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