de Lara-Castells M P, Hernández Marta I, Delgado-Barrio G, Villarreal P, López-Puertas M
Instituto de Matemáticas y Física Fundamental (CSIC), Serrano 123, E-28006 Madrid, Spain.
J Chem Phys. 2006 Apr 28;124(16):164302. doi: 10.1063/1.2189860.
The CO(2)(010)-O((3)P) vibrational energy transfer (VET) efficiency is a key input to aeronomical models of the energy budget of the upper atmospheres of Earth, Venus, and Mars. This work addresses the physical mechanisms responsible for the high efficiency of the VET process at the thermal energies existing in the terrestrial upper atmosphere (150 K</=T</=550 K). We present a quantum-mechanical study of the process within a reduced-dimensionality approach. In this model, all the particles remain along a plane and the O((3)P) atom collides along the C(2v) symmetry axis of CO(2), which can present bending oscillations around the linear arrangement, while the stretching C-O coordinates are kept fixed at their equilibrium values. Two kinds of scattering calculations are performed on high-quality ab initio potential energy surfaces (PESs). In the first approach, the calculations are carried out separately for each one of the three PESs correlating to O((3)P). In the second approach, nonadiabatic effects induced by spin-orbit couplings (SOC) are also accounted for. The results presented here provide an explanation to some of the questions raised by the experiments and aeronomical observations. At thermal energies, nonadiabatic transitions induced by SOC play a key role in causing large VET efficiencies, the process being highly sensitive to the initial fine-structure level of oxygen. At higher energies, the two above-mentioned approaches tend to coincide towards an impulsive Landau-Teller mechanism of the vibrational to translational (V-T) energy transfer.
CO₂(010)-O(³P) 振动能量转移（VET）效率是地球、金星和火星高层大气能量收支天文模型的关键输入参数。这项工作探讨了在地球高层大气中存在的热能（150 K≤T≤550 K）下，导致VET过程高效率的物理机制。我们采用降维方法对该过程进行了量子力学研究。在这个模型中，所有粒子都沿一个平面排列，O(³P) 原子沿着CO₂ 的C₂v 对称轴碰撞，CO₂ 可以围绕线性排列呈现弯曲振荡，而C-O 伸缩坐标则保持在其平衡值。在高质量的从头算势能面（PES）上进行了两种散射计算。在第一种方法中，分别对与O(³P) 相关的三个PES 中的每一个进行计算。在第二种方法中，还考虑了自旋轨道耦合（SOC）引起的非绝热效应。这里给出的结果为实验和天文观测提出的一些问题提供了解释。在热能下，SOC 引起的非绝热跃迁在导致高VET 效率方面起关键作用，该过程对氧的初始精细结构能级高度敏感。在较高能量下，上述两种方法趋向于一致，形成振动到平动（V-T）能量转移的脉冲式朗道-泰勒机制。
