Abstract. Measurements of the fragmentation of deuterium tagged water molecules, namely HDO, by fast proton and F⁷⁺ impact exhibit a very strong isotopic preference for cleavage of the OH bond over the OD bond. Explicitly, the former is about five times more likely than the latter for HDO²⁺ dissociation. HDO⁺ exhibits similar behaviour, though the asymmetry is smaller at about a factor of 2. Wave-packet propagation calculations are in good agreement with the measured branching ratio for HDO²⁺ dissociation.

Print publication: Issue 7 (14 April 2006)
Received 20 September 2005, in final form 9 February 2006
Published 20 March 2006