Houston Paul L, Conte Riccardo, Bowman Joel M
†School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
‡Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, United States.
J Phys Chem A. 2015 May 21;119(20):4695-710. doi: 10.1021/acs.jpca.5b00219. Epub 2015 May 12.
A model for energy transfer in the collision between an atom and a highly excited target molecule has been developed on the basis of classical mechanics and turning point analysis. The predictions of the model have been tested against the results of trajectory calculations for collisions of five different target molecules with argon or helium under a variety of temperatures, collision energies, and initial rotational levels. The model predicts selected moments of the joint probability distribution, P(Jf,ΔE) with an R(2) ≈ 0.90. The calculation is efficient, in most cases taking less than one CPU-hour. The model provides several insights into the energy transfer process. The joint probability distribution is strongly dependent on rotational energy transfer and conservation laws and less dependent on vibrational energy transfer. There are two mechanisms for rotational excitation, one due to motion normal to the intermolecular potential and one due to motion tangential to it and perpendicular to the line of centers. Energy transfer is found to depend strongly on the intermolecular potential and only weakly on the intramolecular potential. Highly efficient collisions are a natural consequence of the energy transfer and arise due to collisions at "sweet spots" in the space of impact parameter and molecular orientation.
基于经典力学和转折点分析，开发了一种用于描述原子与高激发靶分子碰撞中能量转移的模型。该模型的预测结果已与五种不同靶分子在氩气或氦气中，于各种温度、碰撞能量和初始转动能级下的碰撞轨迹计算结果进行了对比检验。该模型预测联合概率分布P(Jf,ΔE)的选定矩，相关系数R(2)约为0.90。计算效率很高，在大多数情况下所需时间不到一个CPU小时。该模型为能量转移过程提供了几个见解。联合概率分布强烈依赖于转动能量转移和守恒定律，而对振动能量转移的依赖性较小。转动激发有两种机制，一种是由于垂直于分子间势的运动，另一种是由于切向于分子间势且垂直于质心连线的运动。发现能量转移强烈依赖于分子间势，而对分子内势的依赖性较弱。高效碰撞是能量转移的自然结果，是由于在碰撞参数和分子取向空间中的“最佳点”处发生碰撞而产生的。
