Isotopic branching ratio for the O++ HD reaction

Abstract

We describe how a rotationally adiabatic capture theory can be adapted to calculate isotopic branching ratios and cross-sections for the reactions O⁺+ HD → OH⁺+ D and O⁺+ HD → OD⁺+ H. The results are in good agreement with those obtained in a guided ion beam mass spectrometer experiment. Furthermore, we predict that the isotopic branching ratios become more significant for lower internal temperatures of the HD molecules. This is related to the strong sensitivity of the cross-sections to the internal rotational states of the HD molecules.