Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria.
Institut für Allgemeine, Anorganische und Theoretische Chemie, und Center for Molecular Biosciences Innsbruck (CMBI), Universität Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
J Chem Phys. 2018 Nov 7;149(17):174310. doi: 10.1063/1.5049680.
Low frequency combination bands of Cl(H) and Cl(D) have been measured in the region between 600 and 1100 cm by infrared predissociation spectroscopy in a cryogenic 22-pole ion trap using a free electron laser at the FELIX Laboratory as a tunable light source. The Cl(H) (Cl(D)) spectrum contains three bands at 773 cm (620 cm), 889 cm (692 cm), and 978 cm (750 cm) with decreasing intensity toward higher photon energies. Comparison of the experimentally determined transition frequencies with anharmonic vibrational self-consistent field and vibrational configuration interaction calculations suggests the assignment of the combination bands v + v, 2v + v, and 3v + v for Cl(H) and 2v + v, 3v + v, and 4v + v for Cl(D), where v is the Cl⋯H stretching fundamental and v is the Cl(H) bend. The observed asymmetric temperature dependent line shape of the v + v transition can be modeled by a series of ∑-∏ ro-vibrational transitions, when substantially decreasing the rotational constant in the vibrationally excited state by 35%. The spectrum of Cl(D) shows a splitting of 7 cm for the strongest band which can be attributed to the tunneling of the ortho/para states of D.
低频组合带的 Cl(H) 和 Cl(D) 在 600 到 1100cm 之间的区域已经通过在 FELIX 实验室使用自由电子激光作为可调光源的低温 22 极离子阱中的红外预解离光谱进行了测量。Cl(H)（Cl(D)）光谱在 773cm（620cm）、889cm（692cm）和 978cm（750cm）处包含三个带，随着光子能量的增加强度降低。将实验确定的跃迁频率与非谐振动自洽场和振动构型相互作用计算进行比较，表明 Cl(H) 的组合带 v + v、2v + v 和 3v + v 和 Cl(D) 的 2v + v、3v + v 和 4v + v 的分配，其中 v 是 Cl⋯H 伸缩基本频率，v 是 Cl(H) 弯曲。当在振动激发态中实质上将转动常数减小 35%时，v + v 跃迁的观察到的不对称温度相关线型可以通过一系列∑-∏罗振跃迁来建模。Cl(D) 的光谱显示最强带的 7cm 分裂，可以归因于 D 的顺反态的隧道效应。
