Isozaki Tasuku, Iga Hiroshi, Suzuki Tadashi, Ichimura Teijiro
Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ohokayama, Meguro-ku, Tokyo 152-8551, Japan.
J Chem Phys. 2007 Jun 7;126(21):214304. doi: 10.1063/1.2736687.
The UV-UV hole-burning spectra of the jet-cooled 1-aminoindan were measured for the first time. Complicated spectral features observed in the laser-induced fluorescence excitation spectrum due to two conformers, R and B, were firmly separated. On the basis of fluorescence measurements and B3LYP/cc-pVTZ calculations, low-frequency ring twisting and ring puckering modes were assigned. These modes are coupled in the S1 state due to the Duschinsky rotation. The Duschinsky matrix was calculated from the normal modes predicted by quantum chemical calculations. The coupling between the twisting and puckering modes for conformer B is stronger than that for conformer R. The twisting mode was observed at 0+99 cm(-1) in the S1 state for conformer B, while not for conformer R. The Franck-Condon activity of the twisting mode substantially differs between the two conformers. The transition to the twisting level for conformer B would be allowed by the Duschinsky rotation. The fluorescence lifetime of conformer vibronic levels was also measured and differed for each conformer.
首次测量了喷射冷却的1-氨基茚的紫外-紫外空穴烧蚀光谱。在激光诱导荧光激发光谱中观察到的由于R和B两种构象体导致的复杂光谱特征被明确分离。基于荧光测量和B3LYP/cc-pVTZ计算，确定了低频环扭转和环褶皱模式。由于杜施insky旋转，这些模式在S1态中相互耦合。杜施insky矩阵由量子化学计算预测的正常模式计算得出。构象体B的扭转和褶皱模式之间的耦合比构象体R更强。在S1态中，构象体B的扭转模式在0+99 cm(-1)处被观察到，而构象体R则未观察到。两种构象体的扭转模式的弗兰克-康登活性有很大差异。通过杜施insky旋转，构象体B向扭转能级的跃迁是允许的。还测量了构象体振转能级的荧光寿命，且每个构象体的荧光寿命不同。
