Interactions and quenching of the excited state-selected metastable atoms neon and argon in collisions with other atoms and molecules are to be studied in crossed supersonic molecular beams. Scattering attributes to be measured include nonreactive scattering angular distributions, angular distributions of excited products, and mass-resolved relative cross sections for Penning ionization, all carried out over a wide range of collision energy. Penning ionization electron spectra are to be measured under conditions of high kinematic resolution . In conjunction with other scattering studies, these results will be used to estimate potential surfaces for more complicated target molecules, as well as to resolve the overall Penning resonance width (lifetime of the complex against ionization) into orbital-specific components. This research program makes an important experimental and theoretical contribution to the understanding of the fundamental reaction dynamics of chemiionization processes. This kind of spectroscopy of excited intermediate states addresses the boundary line where differences and similarities are likely to be found between neutral-neutral and ion-molecule reaction dynamics.
