Experimental and Theoretical Investigations of the Interactions of Alkali Metal Ions with Atmospheric Molecules

摘要

This report includes a theoretical as well as an experimental study of low energy collisions of alkali metal ions with small molecules of atmospheric importance. The initial experimental results on the system Li(6)+ plus H2O showed how inelastic collisions can completely dominate elastic collisions for molecules with large dipole moments. This is in contrast to the small inelastic cross sections for low energy collisions between ions and homonuclear diatomic molecules. As the experimental results became available a parallel theoretical effort was begun to (1) interpret the experimental results in terms of known potential surfaces, (2) investigate thoroughly the effect of inelastic collisions on diffusion processes, (3) develop a theoretical formalism for inelastic ion-molecule collisions and (4) consider vibrational effects by studying the model system He + H2. As the theoretical work proceeded it became clear that experimental studies at as low energies as possible would be most valuable. Accordingly, experimental work on the Li(6)+ plus N2 system at an incident ion energy of 5 eV was begun. Efforts to put the measurements on an absolute scale were also initiated.