Torsion–rotation analysis of OH stretch overtone–torsion combination bands in methanol
Torsion–rotation analysis of OH stretch overtone–torsion combination bands in methanol
复制标题
甲醇中 OH 伸缩泛音 - 扭转组合带的扭转 - 旋转分析
DOI：
--
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
D. S. Perry
中科院分区：
文献类型：
--
作者：
David Rueda;O. Boyarkin;T. Rizzo;I. Mukhopadhyay;D. S. Perry
我们报告了喷射冷却甲醇的 OH 拉伸泛音 2v(1) 和 3v(1) 以及扭转组合 2v(1)+v(12)、2v(1)+2v(12)、3v(1)+v(12) 和 3v(1)+2v(12) 的旋转分辨光谱。光谱是通过红外激光脉冲从振动基态直接激发而获得的。通过红外激光辅助光碎片光谱（IRLAPS）检测由此产生的上态水平中的人口。光谱与赫布斯特哈密顿量的全局拟合产生每个 OH 拉伸激发态的扭转和旋转参数，包括 F、rho、V-3 和 V-6。对于每个 OH 拉伸激发量子，我们发现扭转势垒高度 V-3 增加了 40.9 +/-1.9 cm(-1)，扭转惯性 F 减小了 0.89 +/-0.02 cm(-1)。参考从头计算，我们用甲醇电子结构随着 OH 键伸长而发生的变化来解释 V-3 的增加。对于 Deltav(12)=1，我们仅观察到 DeltaK=+/-1 的转换，对于 Deltav(12)=2，我们仅观察到 DeltaK=0。我们提出了弗兰克-康登模型来解释这些明显的选择规则和强度的总体模式。 (C) 2002 年美国物理研究所。
We report rotationally resolved spectra of jet-cooled methanol for the OH stretch overtones, 2v(1) and 3v(1), and for the torsional combinations, 2v(1)+v(12), 2v(1)+2v(12), 3v(1)+v(12), and 3v(1)+2v(12). The spectra are obtained by direct excitation from the vibrational ground state with an infrared laser pulse. Population in the resulting upper state levels is detected by infrared laser assisted photofragment spectroscopy (IRLAPS). Global fits of the spectra to the Herbst Hamiltonian yield the torsional and rotational parameters, including F, rho, V-3, and V-6, for each OH stretch excited state. For each quantum of OH stretch excitation, we find that the torsional barrier height V-3 increases by 40.9 +/-1.9 cm(-1) and the torsional inertial F decreases by 0.89 +/-0.02 cm(-1). With reference to ab initio calculations, we explain the increase in V-3 in terms of changes in the electronic structure of methanol as the OH bond is elongated. For Deltav(12)=1 we observe only transitions with DeltaK=+/-1, and for Deltav(12)=2 we observe only DeltaK=0. We present a Franck-Condon model to explain these apparent selection rules and the overall pattern of intensity. (C) 2002 American Institute of Physics.