Physikalisch-Chemisches Institut, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany.
J Chem Phys. 2011 Jun 21;134(23):234303. doi: 10.1063/1.3598942.
The [H,C,N] molecular system is a very important model system to many fields of chemical physics and the experimental characterization of highly excited vibrational states of this molecular system is of special interest. This paper reports the experimental characterization of all 3822 eigenenergies up to 6880 cm(-1) relative to the ground state in the HCN part of the potential surface using high temperature hot gas emission spectroscopy. The spectroscopic constants for the first 71 vibrational states including highly excited bending vibrations up to v(2) = 10 are reported. The perturbed eigenenergies for all 20 rotational perturbations in the reported eigenenergy range have been determined. The 11,070 eigenenergies up to J = 90 for the first 123 vibrational substates are included as supplement to this paper. We show that a complete ab initio rovibrational analysis for a polyatomic molecule is possible. Using such an analysis we can understand the molecular physics behind the Schrödinger equation for problems for which perturbation theoretical calculations are no more valid. We show that the vibrational structure of the linear HCN molecule persists approximately up to the isomerization barrier and only above the barrier the accommodation of the vibrational states to the double well structure of the potential takes place.
[H,C,N] 分子体系是化学物理许多领域中非常重要的模型体系，因此实验表征该分子体系的高激发振动态具有特殊的意义。本文报道了使用高温热气体发射光谱法，对势能面中 HCN 部分的所有 3822 个本征能至 6880cm(-1) 相对于基态的实验特性进行了研究。报道了前 71 个振动态（包括高达 v(2)=10 的高激发弯曲振动）的光谱常数。在报道的本征能范围内，所有 20 个转动微扰的微扰本征能已被确定。作为本文的补充，还包括了前 123 个振动子态的第一 11070 个本征能，其 J 值高达 90。我们表明，对于多原子分子，完全从头算的振转分析是可能的。通过这样的分析，我们可以理解薛定谔方程背后的分子物理，而对于那些微扰理论计算不再有效的问题。我们表明，线性 HCN 分子的振动结构在大约异构化势垒处保持不变，只有在势垒上方，振动态才能适应势的双阱结构。
