Lauzin C, Didriche K, Macko P, Demaison J, Liévin J, Herman M
Laboratoire de Chimie quantique et Photophysique, CP160/09, Faculte des Sciences, Universite libre de Bruxelles, Ave. Roosevelt, 50, B-1050, Brussels, Belgium.
J Phys Chem A. 2009 Mar 19;113(11):2359-65. doi: 10.1021/jp8077908.
New theoretical and experimental results on the acetylene-Ar van der Waals complex are presented and the literature is reviewed. New ab initio calculations at the MP2 level were performed using large basis sets with diffuse functions and taking into account the basis set superposition error. It was found that the structure of acetylene is not significantly altered by the complexation and that its vibrational frequencies are only slightly lowered. Finally, it was observed that the calculated properties of the complex (structure, vibrational spectrum, bond dissociation energy) are not sensitive to the structure imposed on acetylene. Experimentally, acetylene-Ar was produced in a supersonic expansion under experimental conditions corresponding to 9 K rotational temperature. Thanks to the performances of CW-CRDS detection, the K(a) = 0 <-- 1, 1 <-- 0, and 2 <-- 1 sub-bands of the nu(1) + nu(3) band could be recorded and resolved and most of their lines assigned. Upper-state rotational constants were fitted, however not including the upper K(a) = 2 state, which shows K-doubling the opposite of the expected. The Lorentzian width of most line profiles sets the mean lifetime to some 7.5 ns. Local perturbations affecting line positions and/or line widths are demonstrated. Additional series of lines tentatively attributed to acetylene-Ar are discussed.
本文给出了乙炔 - 氩范德华复合物的新理论和实验结果，并对相关文献进行了综述。使用带有弥散函数的大基组并考虑基组重叠误差，在MP2水平上进行了新的从头算计算。结果发现，络合作用对乙炔的结构影响不大，其振动频率仅略有降低。最后，观察到复合物的计算性质（结构、振动光谱、键解离能）对强加于乙炔的结构不敏感。在实验上，乙炔 - 氩是在对应于9 K转动温度的实验条件下通过超声速膨胀产生的。由于连续波腔衰荡光谱检测的性能，ν(1)+ν(3)带的K(a)=0←1、1←0和2←1子带得以记录和分辨，并且其大部分谱线得以归属。拟合了上能级转动常数，但不包括上K(a)=2态，该态显示出与预期相反的K - 双重分裂。大多数谱线轮廓的洛伦兹宽度将平均寿命设定为约7.5 ns。展示了影响谱线位置和/或线宽的局部微扰。讨论了初步归因于乙炔 - 氩的其他系列谱线。
