title: Communication: the origin of rotational enhancement effect for the reaction of H2O(+) + H2 (D2).
abstract: We have measured the absolute integral cross sections (σ's) for H3O(+) formed by the reaction of rovibrationally selected H2O(+)(X(2)B1; v1 (+)v2 (+)v3 (+) = 000; N(+) K a (+) K c (+) = 000, 111, and 211) ion with H2 at the center-of-mass collision energy (Ecm) range of 0.03-10.00 eV. The σ(000), σ(111), and σ(211) values thus obtained reveal rotational enhancements at low Ecm < 0.50 eV, in agreement with the observation of the previous study of the H2O(+)(X(2)B1) + D2 reaction. This Communication presents important progress concerning the high-level ab initio quantum calculation of the potential energy surface for the H2O(+)(X(2)B1) + H2 (D2) reactions, which has provided valuable insight into the origin of the rotational enhancement effect. Governed by the charge and dipole-induced-multipole interactions, the calculation shows that H2 (D2) approaches the H end of H2O(+)(X(2)B1) in the long range, whereas chemical force in the short range favors the orientation of H2 (D2) toward the O side of H2O(+). The reorientation of H2O(+) reactant ion facilitated by rotational excitation thus promotes the H2O(+) + H2 (D2) reaction along the minimum energy pathway, rendering the observed rotational enhancement effects. The occurrence of this effect at low Ecm indicates that the long range charge and dipole-induced-multipole interactions of the colliding pair play a significant role in the dynamics of the exothermic H2O(+) + H2 (D2) reactions.
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
authors.forename: Anyang
authors.initials: A
authors.lastname: Li
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
authors.forename: Yongle
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Guo
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Kai-Chung
authors.initials: KC
authors.lastname: Lau
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Xiong
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Yih-Chung
authors.initials: YC
authors.lastname: Chang
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: C Y
authors.initials: CY
authors.lastname: Ng