標題: | Vibrational and rotational structure and excited-state dynamics of pyrene |
作者: | Baba, Masaaki Saitoh, Motohisa Kowaka, Yasuyuki Taguma, Kunio Yoshida, Kazuto Semba, Yosuke Kasahara, Shunji Yamanaka, Takaya Ohshima, Yasuhiro Hsu, Yen-Chu Lin, Sheng Hsien 應用化學系 Department of Applied Chemistry |
關鍵字: | ab initio calculations;excited states;fluorescence;intramolecular mechanics;nonradiative transitions;organic compounds;potential energy surfaces;radiative lifetimes;rotational states;vibrational states;vibronic states;Zeeman effect |
公開日期: | 1-一月-1970 |
摘要: | "Vibrational level structure in the S-0 (1)A(g) and S-1 B-1(3u) states of pyrene was investigated through analysis of fluorescence excitation spectra and dispersed fluorescence spectra for single vibronic level excitation in a supersonic jet and through referring to the results of ab initio theoretical calculation. The vibrational energies are very similar in the both states. We found broad spectral feature in the dispersed fluorescence spectrum for single vibronic level excitation with an excess energy of 730 cm(-1). This indicates that intramolecular vibrational redistribution efficiently occurs at small amounts of excess energy in the S-1 B-1(3u) state of pyrene. We have also observed a rotationally resolved ultrahigh-resolution spectrum of the 0(0)(0) band. Rotational constants have been determined and it has been shown that the pyrene molecule is planar in both the S-0 and S-1 states, and that its geometrical structure does not change significantly upon electronic excitation. Broadening of rotational lines with the magnetic field by the Zeeman splitting of M-J levels was very small, indicating that intersystem crossing to the triplet state is minimal. The long fluorescence lifetime indicates that internal conversion to the S-0 state is also slow. We conclude that the similarity of pyrene's molecular structure and potential energy curve in its S-0 and S-1 states is the main cause of the slow radiationless transitions." |
URI: | http://dx.doi.org/224318 http://hdl.handle.net/11536/16686 |
ISSN: | 0021-9606 |
DOI: | 224318 |
期刊: | JOURNAL OF CHEMICAL PHYSICS |
Volume: | 131 |
Issue: | 22 |
結束頁: | |
顯示於類別: | 期刊論文 |