Internal Energy Effects in Charge Transfer Collisions.

Available from UMI in association with The British Library. A fixed wavelength photoion--photoelectron coincidence apparatus for studying the effect of projectile ion internal energy on collision cross-sections has been developed. The effect of molecular vibration on charge transfer between H_sp{2}{+} and Ar at 20 eV has been investigated and the results interpreted with the aid of a simple theory. Studies of the effect of spin-orbit coupling on symmetric charge transfer in the rare gases have shown that the ratio of the cross-sections for the two spin-orbit levels of the ground state ion sigma(^2P _{1/2})/sigma( ^2P_{3/2} ) are relatively insensitive to collision energy and are 0.94 +/- 0.07 for argon, 0.88 +/- 0.09 for krypton and 0.80 +/- 0.08 for xenon over the collision energy range 5-1000 eV. Results for the effect of H_sp {2}{+} vibrational energy on symmetric charge transfer in hydrogen have been obtained over the kinetic energy range 8-1000 eV and show that the cross-sections vary significantly with vibrational energy in a complicated manner. These results extend and confirm the results of previous non-coincidence experiments. Agreement with current theory for the rare gases is satisfactory; however, results for symmetric charge transfer in hydrogen are not in accord with multistate impact parameter theory. Data of the type obtained with the present technique for individual internal energy states of ionic species is of vital importance in understanding the physics of high temperature plasmas, gas lasers and planetary atmospheres. They are also of importance as they provide a sensitive test of current theories.