Associative ionization in collisions of He+ with H- and D-

Absolute cross sections of the associative ionization in the collision of He+ with H- D- have been measured in a merged beam experiment over a relative velocity interval ranging from 0.4 to 5 x 10(6) cm s(-1). At a given relative velocity, the two cross sections significantly differ at low velocities where the cross section for HeD+ formation exceeds that of HeH+ by as much as 35%. The difference, however, decreases with the velocity and falls in the experimental error above 2 x 10(6) cm s(-1). In both cases the energy dependence becomes compatible at low energy with an E-1 law.