Ultraviolet resonance Raman study of the pyrene S4, S3, and S2 excited electronic states
Ultraviolet resonance Raman study of the pyrene S4, S3, and S2 excited electronic states
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芘 S4、S3 和 S2 激发电子态的紫外共振拉曼研究
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
S. Asher
中科院分区：
文献类型：
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作者：
Colleen M. Jones;S. Asher
在Py的S2、S3和S4π→π*电子跃迁中的紫外共振拉曼激发导致了完全对称的环振动的强烈增强。在这些电子跃迁中最强烈增强的拉曼模式来自于在吸收光谱中表现出Frank-Condon振动结构的振动。1597厘米−1(B3g)模在S3和S4跃迁之间以及由于这些对称性允许态之间的赫兹伯格-泰勒耦合而在S2和S3跃迁之间显示出选择性的增强。如果计入非密码子贡献，实验观察到的全对称Py基团的S4共振拉曼激发谱与用共振拉曼变换理论计算的S4共振拉曼激发谱非常接近。我们发现非密码子的贡献随着振动频率的增加而增加，这表明非绝热振动相互作用。由于激光激发源的高能流入射，导致了由高能量流密度引起的Py拉曼强度饱和现象。
UV resonance Raman excitation within the S2, S3, and S4 π→π* electronic transitions of pyrene results in strong enhancement of totally symmetric ring vibrations. The Raman modes most strongly enhanced within these electronic transitions derive from vibrations exhibiting Franck–Condon vibronic structure in the absorption spectrum. The 1597 cm−1 (b3g) mode shows selective enhancement between the S3 and S4 transitions, and between the S2 and S3 transitions due to Herzberg–Teller coupling between these symmetry‐allowed states. The experimentally observed S4 resonance Raman excitation profiles of the totally symmetric pyrene fundamentals agree closely with those calculated using resonance Raman transform theory if non‐Condon contributions are included. We see an increased non‐Condon contribution with an increasing vibrational frequency, indicating nonadiabatic vibronic interactions. The high incident energy fluxes of the Nd‐YAG laser‐based excitation source cause saturation of the pyrene Raman intensities sinc...