Collision-Induced Electronic Energy Transfer in Small Molecules (Chemistry)

Dagdigian博士，与米勒德亚历山大博士合作， 马里兰州大学，计划继续联合 理论实验项目，涉及研究 小分子电子非弹性碰撞过程 和激进分子 实验将涉及使用 光-光双共振测定 具有初始和最终量子的能量转移速率常数 流系统中的状态解析。 以下碰撞 将研究的过程：（a）之间的过渡 氮的低三重态，（B）之间的跃迁 CN和一氧化碳正离子的低位态，（c） CS中的自旋变化跃迁，以及（d） 一卤化钙的激发态。 该实验 正在与下列机构联合开展工作： 理论项目：（a）开发完全量子 电子非弹性碰撞的描述， 特别是那些涉及改变自旋多重性的 分子伴侣，（B）从头算电位的确定 能量面和波函数 电子激发的CN和氮，以及（c）计算 基于从头算的完全态分辨截面 潜在的表面 目前正在特别注意 电子非绝热矩阵元的计算 它描述的是 碰撞伙伴及其组成部分的运动 电子。 这项研究很重要，因为 研究负责电子 分子的激发态和压力依赖性 在许多荧光反应中的光子产率。 比如说， 长期以来，人们一直有兴趣了解 控制系统中能量流动的详细机制 含有电子激发的氮分子。 因为它 是我们大气层的主要组成部分， 氮的碰撞过程对于 对极光和气辉等现象的理解。 在 在实验室中，氮气通常存在于气体混合物中， 放电，包括各种气体激光介质。

Dr. Dagdigian, in collaboration with Dr. Millard Alexander of the University of Maryland, plans to continue a joint theoretical-experimental project involving studies of electronically inelastic collision processes in small molecules and radicals. The experiments will involve the use of optical-optical double resonance for the determination of energy transfer rate constants with initial and final quantum state resolution in a flow system. The following collisional processes will be investigated: (a) transitions between low-lying triplet states of nitrogen, (b) transitions among low-lying states of CN and carbon monoxide positive ions, (c) spin-changing transitions in CS, and (d) transitions between excited states of the calcium monohalides. This experimental work is being carried out jointly with the following theoretical projects: (a) the development of the fully quantum description of electronically inelastic collisions, in particular those involving a change in spin multiplicity of the molecular partner, (b) the determination of ab initio potential energy surfaces and wavefunctions relevant to collisions of electronically excited CN and nitrogen, and (c) the calculation of fully state-resolved cross sections based on ab initio potential surfaces. Specific attention is being given to the calculation of the electronically nonadiabatic matrix elements which describe the coupling between the nuclear motion of the collision partners and the motion of their constituent electrons. This research is important because the processes under investigation are responsible for quenching of electronically excited states of molecules and for the pressure dependence of photon yields in many chemiluminescent reactions. For example, there has been a long-standing interest in understanding the detailed mechanisms that govern energy flow in systems containing electronically excited nitrogen molecules. Since it is the major component of our atmosphere, knowledge about collisional processes of nitrogen is crucial for an understanding of phenomena such as auroras and airglows. In the laboratory, nitrogen is often present in gas mixtures in discharges, including various gas laser media.