Butler Phillip, Moss David B, Yin Hongming, Schmidt Timothy W, Kable Scott H
School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia.
J Chem Phys. 2007 Sep 7;127(9):094303. doi: 10.1063/1.2759931.
A detailed study of the S1((1)B2)-S0((1)A1) electronic transition of jet-cooled fluorobenzene has been carried out using laser-induced fluorescence and dispersed fluorescence (DF) spectroscopies. Analysis of over 40 single vibronic level DF spectra resulted in the assignment of 16 fundamental frequencies in the excited electronic state. Progressions in totally symmetric modes, particularly in the ring-breathing mode nu9, feature in both types of fluorescence spectrum. There is also significant activity in non-totally-symmetric modes, with activity in Franck-Condon (FC)-allowed overtones, FC-forbidden combinations induced by Duschinsky mixing, and symmetry-forbidden transitions induced by the same Herzberg-Teller vibronic coupling mechanism that induces the benzene S1-S0 transition. Fermi resonances (FRs) are extensive throughout the spectrum, especially in the important FC-active a1 modes. A consequence of these extensive FRs is that several important previous assignments are shown to be incorrect and have been reassigned here. Ab initio and density functional theory calculations have also been performed to support the experimental assignments.
利用激光诱导荧光和色散荧光（DF）光谱技术，对喷射冷却的氟苯的S1((1)B2)-S0((1)A1)电子跃迁进行了详细研究。对40多个单振动能级DF光谱的分析，确定了激发电子态中的16个基频。全对称模式的跃迁，特别是在环呼吸模式ν9中的跃迁，在两种类型的荧光光谱中都有特征。非全对称模式也有显著活性，包括弗兰克-康登（FC）允许的泛音、由杜申斯基混合诱导的FC禁止组合，以及由诱导苯S1-S0跃迁的相同赫兹伯格-泰勒振动耦合机制诱导的对称禁止跃迁。费米共振（FR）在整个光谱中广泛存在，特别是在重要的FC活性a1模式中。这些广泛的FR的一个结果是，以前的几个重要归属被证明是错误的，在此重新进行了归属。还进行了从头算和密度泛函理论计算以支持实验归属。
