Electronic Nonadiabaticity in Chemical Dynamics

化学动力学中的电子非绝热性

• 批准号: 9629385
• 负责人: Millard Alexander
• 金额: $ 35.68万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-08-01 至 1999-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9629385&HistoricalAwards=false
• 关键词: Electronic; Nonadiabaticity; Chemical; Dynamics

Millard H. Alexander of The University of Maryland at College Park and Paul J. Dagdigian of Johns Hopkins University are supported by the Experimental Physical Chemistry Program to continue their collaborative studies of the dynamics of nonreactive collisions involving diatomic free radicals, with an emphasis on electronically nonadiabatic processes. They will study weakly bound complexes of the radicals and the predissociation of these complexes in order to gain further information on the underlying potential energy surfaces. The theoretical effort involves development and application of new methods for elucidating the mechanism of molecular collisions and photodissociation, ab initio calculation of the potential energy surfaces and nonadiabatic coupling matrix elements, and full quantum calculations of cross sections and rate constants and the determination of bend-stretch levels of weakly-bound complexes. The experimental effort involves the determination of state-to-state inelastic cross sections for energy transfer processes and the spectroscopy and dynamics of rare gas-diatomic van der Waals complexes. The dominant theme of their research is the influence of electronic angular momentum and/or spin on inelastic energy transfer and photodissociation. During a collision, or during the breakup of a molecule, the internal electronic angular momenta will couple with the motion of the nuclei and hence influence product branching ratios and inelastic propensities. Therefore, a thorough understanding of this coupling mechanism should ultimately lead to a better understanding of how to optimize the desired products in chemical reactions.

马里兰大学帕克分校的米勒德·H·亚历山大和约翰·霍普金斯大学的保罗·J·达格迪吉安得到了实验物理化学计划的支持，他们将继续合作研究涉及双原子自由基的非反应性碰撞的动力学，重点是电子非绝热过程。他们将研究自由基的弱结合络合物和这些络合物的预解离，以获得关于潜在势能面的进一步信息。理论工作包括发展和应用新的方法来阐明分子碰撞和光解的机制，势能面和非绝热耦合矩阵元的从头计算，截面和速率常数的全量子计算以及弱结合络合物的弯曲-拉伸能级的测定。实验工作包括确定能量转移过程的态到态非弹性截面，以及稀有气体-双原子范德华络合物的光谱和动力学。他们研究的主要主题是电子角动量和/或自旋对非弹性能量转移和光解离的影响。在碰撞过程中，或在分子分裂过程中，内部电子角动量将与原子核的运动相耦合，从而影响产物的分支比和非弹性倾向。因此，对这种偶联机理的透彻理解最终应该会导致更好地理解如何在化学反应中优化所需的产物。