Communication: the origin of rotational enhancement effect for the reaction of H2O(+) + H2 (D2)

• Published in: The Journal of chemical physics 2014-01, Vol.140 (1), p.011102-011102
• Main Authors: Li, Anyang, Li, Yongle, Guo, Hua, Lau, Kai-Chung, Xu, Yuntao, Xiong, Bo, Chang, Yih-Chung, Ng, C Y
• Format: Article
• Language: English
• Subjects: Collision dynamics; Dipoles; Exothermic reactions; Mathematical analysis; Organic chemistry; Potential energy
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.4861002

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.