title: Communication: Rovibrationally selected absolute total cross sections for the reaction H2O(+)(X2B1; v1(+)v2(+)v3(+) = 000; N+(Ka+Kc+)) + D2: observation of the rotational enhancement effect.
abstract: By employing the newly established vacuum ultraviolet laser pulsed field ionization-photoion (PFI-PI) double quadrupole-double octopole ion guide apparatus, we have measured the rovibrationally selected absolute total cross sections of the ion-molecule reaction H(2)O(+)(X(2)B(1); v(1)(+)v(2)(+)v(3)(+) = 000; N(+)(Ka+Kc+)) + D(2) → H(2)DO(+) + D in the center-of-mass collision energy (E(cm)) range of 0.05-10.00 eV. The pulsing scheme used for the generation of PFI-PIs has made possible the preparation of reactant H(2)O(+)(X(2)B(1); v(1)(+)v(2)(+)v(3)(+) = 000) ions in single N(+)(Ka+Kc+) rotational levels with high kinetic energy resolutions. The absolute total cross sections observed in different N(+)(Ka+Kc+) levels with rotational energies in the range of 0-200 cm(-1) were found to exhibit a significant rotational enhancement on the reactivity for the titled reaction. In contrast, the measured cross sections reveal a decreasing trend with increasing E(cm), indicating that the rotational enhancement observed is not a total energy effect, but a dynamical effect. Furthermore, the rotational enhancement is found to be more pronounced as E(cm) is decreased. This experiment provided evidence that the coupling of the core rotational angular momentum with the orbital angular momentum could play a role in chemical reactivity, particularly at low E(cm).
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Xu
authors.forename: Bo
authors.initials: B
authors.lastname: Xiong
authors.forename: Yih Chung
authors.initials: YC
authors.lastname: Chang
authors.forename: C Y
authors.initials: CY
authors.lastname: Ng