Temperature dependence of binary and ternary recombination of D _3~+ ions with electrons

摘要

Flowing and stationary afterglow experiments were performed to study the recombination of D~3+ ions with electrons at temperatures from 77 to 300 K. A linear dependence of apparent (effective) binary recombination rate coefficients on the pressure of the helium buffer gas was observed. Binary (D_3~+ + e~-) and ternary (D_3~+ + e~- +He) recombination rate coefficients were derived. The obtained binary rate coefficient agrees with recent theoretical values for dissociative recombination of D_3~+. We describe the observed ternary process by a mechanism with two rate determining steps. In the first step, a rotationally excited long-lived neutral D_3 is formed in D_3~+ - e~- collisions. As the second step, the D_3 collides with a helium atom that prevents autoionization of D _3. We calculate lifetimes of D_3 formed from ortho-, para-, or metastates of D_3~+ and use the lifetimes to calculate ternary recombination rate coefficients.