Pugliesi Igor, Tonge Nicola M, Cockett Martin C R
Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
J Chem Phys. 2008 Sep 14;129(10):104303. doi: 10.1063/1.2970092.
This work combines high level ab initio calculations with multidimensional Franck-Condon calculations to refine and augment previous assignments of the lower wavenumber region of the A (1)B(2) <-- X (1)A(1) band system of fluorobenzene. The strength of the assignment has been greatly assisted by the use of zero electron kinetic energy spectroscopy in a series of pump-probe experiments where the response of the molecule to selective excitation in specific modes prior to ionization has been studied. The net result of this analysis is the reassignment of 7 of the 12 previously assigned bands in the region below about 1000 cm(-1) using a strategy that aims to trace the origins of excited state normal modes of fluorobenzene to the well-known Wilson modes of benzene by taking full account of the Duschinsky mixing that accompanies electronic excitation. Duschinsky normal mode analyses of the ground and first excited states of fluorobenzene as well as the electronic ground state of fluorobenzene cation have shown that the common use of the benzene Wilson notation to describe normal modes of this prototypical benzene derivative is highly questionable, particularly following electronic excitation and ionization.
这项工作将高水平的从头算计算与多维弗兰克 - 康登计算相结合，以完善和扩充先前对氟苯A (1)B(2) ← X (1)A(1) 能带系统低波数区域的归属。在一系列泵浦 - 探测实验中使用零电子动能光谱极大地辅助了归属的确定，在这些实验中研究了分子在电离前对特定模式下选择性激发的响应。该分析的最终结果是，利用一种策略对约1000 cm(-1) 以下区域中先前归属的12条谱带中的7条进行了重新归属，该策略旨在通过充分考虑伴随电子激发的杜申斯基混合，将氟苯激发态简正模式的起源追溯到苯的著名威尔逊模式。氟苯基态和第一激发态以及氟苯阳离子基态的杜申斯基简正模式分析表明，常用苯的威尔逊符号来描述这种典型苯衍生物的简正模式是非常值得怀疑的，尤其是在电子激发和电离之后。
