Comparison of experimental and theoretical quantum-state-selected integral cross-sections for the H2O(+) + H2 (D2) reactions in the collision energy range of 0.04-10.00 eV.

To understand the dynamics of H3O(+) formation, we report a combined experimental-theoretical study of the rovibrationally state-selected ion-molecule reactions H2O(+)(X(2)B1; v1(+)v2(+)v3(+); NKa(+)Kc(+)(+)) + H2 (D2) → H3O(+) (H2DO(+)) + H (D), where (v1(+)v2(+)v3(+)) = (000), (020), and (100) and NKa(+)Kc(+)(+) = 000, 111, and 211. Both quantum dynamics and quasi-classical trajectory calculations were carried out on an accurate full-dimensional ab initio global potential energy surface, which involves nine degrees of freedom. The theoretical results are in good agreement with experimental measurements of the initial state specific integral cross-sections for the formation of H3O(+) (H2DO(+)) and thus provide valuable insights into the surprising rotational enhancement and vibrational inhibition effects in these prototypical ion-molecule reactions that play a key role in the interstellar generation of OH and H2O species.