The reaction of O(S) ions with H, HD, and D at low temperatures: Experimental study of the isotope effect.

The reactions of the O ions in the S electronic ground state with D and HD were studied in a cryogenic 22-pole radio-frequency ion trap in the temperature range of 15 K-300 K. The obtained reaction rate coefficients for both reactions are, considering the experimental errors, nearly independent of temperature and close to the values of the corresponding Langevin collisional reaction rate coefficients. The obtained branching ratios for the production of OH and OD in the reaction of O(S) with HD do not change significantly with temperature and are consistent with the results obtained at higher collisional energies by other groups. Particular attention was given to ensure that the O ions in the trap are in the ground electronic state.