Isotope effects in the CO dimer: millimeter wave spectrum and rovibrational calculations of (12C18O)2.
Isotope effects in the CO dimer: millimeter wave spectrum and rovibrational calculations of (12C18O)2.
复制标题
CO 二聚体中的同位素效应：(12C18O)2 的毫米波光谱和振动计算。
DOI：
10.1063/1.2345202
复制
发表时间：
2006
影响因子：
4.4
通讯作者：
A. van der Avoird
中科院分区：
文献类型：
--
作者：
L. Surin;D. N. Fourzikov;T. Giesen;S. Schlemmer;G. Winnewisser;V. Panfilov;B. S. Dumesh;G. Vissers;A. van der Avoird
用Orotron JET光谱仪研究了同位素取代的CO二聚体(12C18O)2的毫米波光谱，证实并推广了以前的红外研究[A.R.W.McKella，J.Mol]。分光度计。226、190(2004年)]。用Ne中CO的非常稀薄的混合气体，使得12C18O样品气体的消耗量很小，并产生冷而简单的光谱。利用组合差分技术，结合红外工作数据，对84-127 GHz范围内的6个跃迁进行了归属。它们属于两个分支，将四个低水平的A+对称性连接到三个以前未知的A-对称性水平。A对称性的最低态的发现，对应于总角动量J在分子间轴上的投影K=0，确定了12C18O二聚体在3.607 cm(-1)处的齿轮弯曲模。随之而来的是使用最近发展的来自从头算耦合团簇的杂化势的旋振计算[CCSD(T)]和对称性适应的微扰理论计算[G.W.M.Visser等人，J.化学]。太棒了。054306(2005年)]与实验给出了很好的一致性。当18O或13C被取代到正常的(12C16O)2同位素时，A+/A-能量分裂、分子间分离R和两个基态异构体的能量差随同位素的变化而显著变化[L.A.Surin等，J.Mol.分光度计。223,132(2004)]，通过这些计算得到了解释。结果表明，分子间势相对于移位的单体质心的各向异性的变化特别显著。
The millimeter wave spectrum of the isotopically substituted CO dimer, (12C18O)2, was studied with the Orotron jet spectrometer, confirming and extending a previous infrared study [A. R. W. McKellar, J. Mol. Spectrosc. 226, 190 (2004)]. A very dilute gas mixture of CO in Ne was used, which resulted in small consumption of 12C18O sample gas and produced cold and simple spectra. Using the technique of combination differences together with the data from the infrared work, six transitions in the 84-127 GHz region have been assigned. They belong to two branches, which connect four low levels of A+ symmetry to three previously unknown levels of A- symmetry. The discovery of the lowest state of A- symmetry, which corresponds to the projection K=0 of the total angular momentum J onto the intermolecular axis, identifies the geared bending mode of the 12C18O dimer at 3.607 cm(-1). Accompanying rovibrational calculations using a recently developed hybrid potential from ab initio coupled cluster [CCSD(T)] and symmetry-adapted perturbation theory calculations [G. W. M. Vissers et al., J. Chem. Phys. 122, 054306 (2005)] gave very good agreement with experiment. The isotopic dependence of the A+/A- energy splitting, the intermolecular separation R, and the energy difference of two ground state isomers, which change significantly when 18O or 13C are substituted into the normal (12C16O)2 isotopolog [L. A. Surin et al., J. Mol. Spectrosc. 223, 132 (2004)], was explained by these calculations. It turns out that the change in anisotropy of the intermolecular potential with respect to the shifted monomer centers of mass is particularly significant.