Ultrafast Transient Raman Investigations of Dynamic Solvent Effects on Chemical Reactivity in Supercritical Fluids

约翰·B·霍普金斯博士和卡尔·F·克诺普夫博士得到了理论和计算化学计划的资助，他们对超临界流体中发生的反应进行了超快瞬时拉曼光谱研究。本研究的目的是了解溶剂在凝聚相化学反应中所起的作用。研究的重点是考察原子和小多原子溶剂临界点附近的溶剂对化学动力学的影响。霍普金斯和克诺普夫博士将尝试通过直接测量双原子溶质分子中振动能弛豫的密度依赖关系来表征临界点附近无限稀溶质分子周围团簇中的局部溶剂密度。他们还将利用超快激光研究光解和双键复合反应，研究局部溶剂密度对化学动力学的影响。直接的实时研究将集中于了解1)溶剂团簇和动态密度波动，2)范德华络合物，以及3)能量转移在决定不同流体密度下的反应性方面的作用。

Drs. John B. Hopkins and Carl F. Knopf are supported by a grant from the Theoretical and Computational Chemistry Program to perform ultrafast transient Raman spectroscopic investigations of reactions occuring in supercritical fluids. The goal of this research is to understand the role which solvent plays in condensed phase chemical reactions. The main thrust of the research is to investigate solvent effects on chemical dynamics near the critical point of atomic and small polyatomic solvents. Drs. Hopkins and Knopf will attempt to characterize the local solvent density in clusters surrounding infinitely dilute solute molecules near the critical point by directly measuring the density dependence of vibrational energy relaxation in diatomic solute molecules. They will also investigate the effect of local solvent density on chemical dynamics using ultrafast laser studies of photodissociation and geminate recombination reactions. Direct real time investigations will focus on understanding the role of 1) solvent clusters and dynamic density fluctuations, 2) van der Waals complexes, and 3) energy transfer in determining reactivity at different fluid densities.