Ultracold inelastic atomic collisions: Threshold relaxation of O(^{3}P_{0}) by He

Abstract

Relaxation of $\mathrm{O}{(}^{3}{P}_{j=0})$ by collisions with He at ultracold temperatures is investigated, and it is illustrated that cross sections and rate constants for the $j=\stackrel{\ensuremath{\rightarrow}}{0}j=2$ and $j=\stackrel{\ensuremath{\rightarrow}}{0}j=1$ transitions exhibit qualitatively different threshold behaviors stemming from the different mechanisms of these nonadiabatic transitions. The results allow us to make the conclusion that, in general, rate constants for the nonadiabatic transitions governed by electrostatic couplings should obey Wigner's threshold law for s-wave scattering approaching a finite value at $\stackrel{\ensuremath{\rightarrow}}{T}0\mathrm{K},$ while cross sections and rate constants for the transitions determined by Coriolis couplings should vanish in the zero-temperature limit.