PHOTOINITIATED PROCESSES IN COMPLEXES - SUBPICOSECOND STUDIES OF CO2-HI AND STEREOSPECIFICITY IN AR-HX

Build-up times for the OH product of photoinduced reactions in CO2-HI complexes were measured for the photolysis wavelength range 235-263 nm by using the subpicosecond resolution pump-probe method pioneered by Zewail and co-workers. There is reasonable accord with.theory and rece nt results from crossed-molecular-beams experiments. To illustrate the squeezed-atom effect, complementary measurements of hydrogen atom tra nslational-energy distributions were carried out by using the high res olution high-n Rydberg time-of-flight (HRTOF) method of Welge and co-w orkers. Prototypical cases of Ar-HBr and Ar-HI complexes are reported. The former illustrates the squeezed-atom effect or caging of the exit ing hydrogen. The latter is dominated by the formation of radical-mole cule complexes. Extensions to other radical-molecule complexes are dis cussed.