The ν6 fundamental frequency of the à state of formaldehyde and Coriolis perturbations in the 3ν4 level.
The ν6 fundamental frequency of the à state of formaldehyde and Coriolis perturbations in the 3ν4 level.
复制标题
甲醛 à 状态的 ν6 基频和 3ν4 级的科里奥利扰动。
DOI：
10.1063/1.4948635
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Tim Schäfer
中科院分区：
文献类型：
--
作者：
G. B. Park;Bastian C. Krüger;S. Meyer;D. Schwarzer;Tim Schäfer
甲醛是含有羰基官能团的最小的稳定有机分子，通常被认为是多原子分子高分辨光谱研究的原型。基电子态的近简并ν4和ν6(分别为面外和面内摆动模)之间的a轴科里奥利相互作用受到了广泛的关注和深入的了解。在第一受激单重态 (1)A2电子态中，没有发生类似的科里奥利相互作用，这是因为该电子态经历了伪扬特勒扭曲，这导致了Q4(‘)面外坐标中的双势垒势能结构，并显著降低了有效ν4(’)频率。在正状态下，ν4(‘)频率降低得如此之大，以至于它是与ν6(’)接近简并的3ν4(‘)泛音。在目前的工作中，我们报道了ν6(‘)在奥态下的精确基频，并确定了3ν4(’)和ν6(‘)之间a轴科里奥利相互作用的强度。我们还对ν4(‘)+ν6(’)组合带进行了旋转分析，该带通过额外的c轴科里奥利扰动与3ν4(‘)相互作用，使我们能够完全解扰适合3ν4(’)的旋转结构。知道奥态中最低能级之间的科里奥利相互作用强度将有助于解释许多被类似相互作用扰动的更高能级结构的光谱和动力学。
Formaldehyde is the smallest stable organic molecule containing the carbonyl functional group and is commonly considered to be a prototype for the study of high-resolution spectroscopy of polyatomic molecules. The a-axis Coriolis interaction between the near-degenerate ν4 and ν6 (out-of-plane and in-plane wagging modes, respectively) of the ground electronic state has received extensive attention and is thoroughly understood. In the first excited singlet à (1)A2 electronic state, the analogous Coriolis interaction does not occur, because the à state suffers from a pseudo-Jahn-Teller distortion, which causes a double-well potential energy structure in the q4 (') out-of-plane coordinate, and which dramatically reduces the effective ν4 (') frequency. The ν4 (') frequency is reduced by such a great extent in the à state that it is the 3ν4 (') overtone which is near degenerate with ν6 ('). In the current work, we report the precise ν6 (') fundamental frequency in the à state, and we determine the strength of the a-axis Coriolis interaction between 3ν4 (') and ν6 ('). We also provide a rotational analysis of the ν4 (')+ν6 (') combination band, which interacts with 3ν4 (') via an additional c-axis Coriolis perturbation, and which allows us to provide a complete deperturbed fit to the 3ν4 (') rotational structure. Knowledge of the Coriolis interaction strengths among the lowest-lying levels in the à state will aid the interpretation of the spectroscopy and dynamics of many higher-lying band structures, which are perturbed by analogous interactions.