Time Resolved Studies of Molecular Clusters (Chemistry)

Drs。Bernstein和Kelley计划研究在超音速分子射流中制备和分离的分子和分子簇的时间分辨光物理和光化学。这项工作将集中在溶质-溶剂团簇和溶质二聚体的超音速分子射流光谱研究上，也将涉及简单化学反应和分子内动力学的时间分辨（皮秒）光谱。分子射流产生非常冷的分子和团簇，通过荧光激发、分散发射和双色飞行时间质谱等技术易于进行光学光谱表征。低温溶液在研究液体状态和一般溶液现象方面具有特殊的光谱学意义。已知的分子体系可以用作溶剂的稀释光谱探针，并且溶液的低温允许人们获得优异的液态光谱分辨率。可以从光谱上观察团簇、二聚体和范德华分子的形成；本质上，溶液中成核和沉淀过程的初步阶段可以用光谱来跟踪。

Drs. Bernstein and Kelley plan a study of the time resolved photophysics and photochemistry of molecules and molecular clusters prepared and isolated in a supersonic molecular jet. The work will be centered about supersonic molecular jet spectroscopic studies of solute-solvent clusters and solute dimers and will also deal with time resolved (picosecond) spectroscopy of simple chemical reactions and intramolecular dynamics. The molecular jet produces very cold molecules and clusters isolated for easy optical spectroscopic characterization by techniques including fluorescence excitation, dispersed emission, and two-color time of flight mass spectroscopy. Cryogenic solutions are of particular spectroscopic interest for the study of the liquid state, and solution phenomena in general. Well known molecular systems can be employed as dilute spectroscopic probes of the solvent, and the low temperature of the solution allows one to obtain excellent liquid state spectroscopic resolution. It is possible to observe spectroscopically the formation of clusters, dimers, and van der Waals molecules; in essence, the preliminary stages of nucleation and precipitation processes in solution can be followed spectroscopically.