Chemiionization in collisions of He(23S) and He(21S) metastable atoms with H and H2

Abstract
A modulated crossed-beams apparatus has been used to measure total cross sections for chemiionization in thermal energy collisions of He(23S) and He(21S) metastable atoms with hydrogen atoms and molecules. In addition, partial cross sections have been measured for reactions in which specified product ions are formed. Results for hydrogen atoms are in good agreement with recent calculations.