Electronic and rotational energy transfer in F(2P1/2)+H2 collisions at ultracold temperatures

Abstract

The dynamics of F(2P1/2)+H2 scattering at ultracold temperatures is studied. It is shown that both the rotational and vibrational excitation of H2 molecules decrease substantially the efficiency of spin–orbit relaxation in F+H2 collisions. It is observed that the near-resonant electronic transition leading to rotational excitation of H2(j=0) is of the same magnitude at high energies as the off-resonant transition in which the rotational angular momentum of H2 is preserved but becomes dominant in ultracold collisions. The zero temperature rate constant for spin-orbit relaxation of F is computed and suggestions are made as to the chemical reactivity of F(2P1/2) atoms at ultracold temperatures. It is found that rotational relaxation of excited H2 molecules is significantly enhanced by electronic transitions in F atoms and the electronic relaxation in F(2P1/2)+H2(j>0) collisions is suppressed by rotational relaxation of H2.