Product-state distributions in dissociative recombination of 3HeD+ and 4HeH+

Asymptotic atomic-state branching ratios for the dissociative recombination of both ³HeD⁺ and ⁴HeH⁺ have been studied using the CRYRING and TSR heavy-ion storage rings. The kinetic-energy release in the recombination process was measured for incident electron energies between 0 and 15 eV. It was found that the He(1s²)+D,H(n=2) channel completely dominates at zero electron energy. The branching ratios observed slightly above the threshold for the n = 3 state of the H (D) atom indicate a rapid switchover of the final-state population to this level. At collision energies above 10 eV many channels leading to excited He atoms are found to contribute, and also a strong angular anisotropy of the dissociation products is observed.