Gas-Phase Reaction Rates at Low Temperatures (300 - 1 K)

在实验物理化学项目的支持下，亚利桑那大学的马克·史密斯正在继续他对低温反应动力学的研究。在过去，他使用共振增强的多光子电离探测来研究(a)在极低温度下自由射流中中性分子或自由基的碰撞，以及(b)在80到250K之间的脉冲平衡轴对称超音速流动反应器（Laval喷嘴）中的自由基反应。接下来，他将通过结合单态制备和/或状态选择探针来扩展自由射流研究。他还将继续研究60-300K羟基自由基、氯原子和其他含氧自由基与各种大气相关反应物的化学反应。广泛的基础研究将在300和1K之间的温度气相化学反应的机理和动力学。这项工作的主要目标包括改进对极低能量碰撞现象的发展理解，以及提供绝对反应速率和产物分支比。这种测量对于行星大气、彗星、星周和星际化学环境的建模是非常需要的。

With support from the Experimental Physical Chemistry Program, Mark Smith of The University of Arizona is continuing his studies on the kinetics of low temperature reactions. In the past, he has used resonance-enhanced multiphoton ionization detection to study (a) collisions of neutral molecules or radicals in a free jet at very low temperatures, and (b) radical reactions in a pulsed equilibrium axisymmetric supersonic flow reactor (Laval nozzle) between 80 and 250K. Next, he will extend the free jet studies by incorporating single-state preparation and/or state-selective probes. He will also continue his investigations of the 60-300K chemistry of hydroxyl radicals, chlorine atoms and other reactive oxygen-containing radicals with a variety of atmospherically relevant reactants. Broad based investigations will be made into the mechanism and dynamics of gas phase chemical reactions at temperatures between 300 and 1K. The primary goals of this work include the refinement of the developing understanding of very low energy collision phenomena as well as the provision of absolute reaction rates and product branching ratios. Such measurements are critically needed for the modeling of planetary atmospheric, cometary, circumstellar and interstellar chemical environments.