KINETIC AND ELECTRONIC-ENERGY DEPENDENCE OF THE REACTION OF V+ WITH D2O

The reaction of V+ with D2O is studied as a function of translational energy in a guided-ion-beam tandem mass spectrometer. Three ionic prod ucts are formed: VD+, VO+, and VOD+. The effect of electronic energy i s probed by varying the conditions used for forming V+. The a(3)F stat e of V+ reacts much more efficiently than the a(5)D ground state in fo rming all three product ions. Indeed, excited triplet states of V+ deh ydrogenate D2O to form VO+ + D-2 very efficiently, while this reaction is not observed for V+(a(5)D) even though the reaction is exothermic. These results are consistent with a recent study of the reverse react ion of VO+ + D-2 [J. Phys. Chem. 1993, 97, 544]. State-specific cross sections suggest that the reaction occurs primarily through a triplet state D-V+-OD intermediate and can be explained by using molecular-orb ital and spin-conservation concepts. The t;reshold for endothermic for mation of VOD+ is interpreted to give D-0(V+-OD) = 4.41 +/- 0.19 eV.