HR: 1330h
AN: SA43A-04    [Abstracts]
TI: A new mechanism for the production of highly vibrationally excited OH in the mesosphere: An ab initio study of the reactions of O₂ (A ³ Σ⁺_u and A^{' 3} Δ_u) + H
AU: * Sharma, R D
EM: ramesh.sharma@hanscom.af.mil
AF: Air Force Research Laboratory/VSBYB, 29 Randolph Road, Hannscom AFB, MA 01890
AU: Liu, J
AF: Department of Chemistry, Emory University, Atlanta, GA 30322
AU: Zhang, P
AF: Department of Chemistry, Emory University, Atlanta, GA 30322
AU: Morokuma, K
AF: Department of Chemistry, Emory University, Atlanta, GA 30322
AB: In an attempt to explain the observed nightglow emission from OH (v=10) in the mesosphere that has energy greater than the expthermicity of the H + O₃ reaction, potential energy surfaces were calculated for the reactions fo high lying electronic states of O₂(A³Σ⁺_u and A^{' 3}Δ_u) with atomic hydrogen H(²S) to produce the ground state products OH(²Π) + O(³P). From collinear two-dimensional scans, several adiabatic and nonadiabatic pathways have been identified. Multi-configurational single and double excitation configuration interaction calculations show that the adiabatic pathways on a ⁴Δ potential surface from O₂(A^{' 3}Δ) + H and a ⁴Σ⁺ potential surface from O₂ (A ³Σ⁺_u) + H are the most favorable, with the zero-point corrected barrier heights of as low as 0.191 eV and 0.182 eV, respectively, and the reactions are fast. The transition states for these pathways are collinear and early, and the reaction coordinate suggests that the potential energy release of ca. 3.8 eV (larger than the energy to excite OH to v=10) is likely to favor high vibrational excitation.
DE: 0310 Airglow and aurora
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0342 Middle atmosphere--energy deposition
SC: SPA-Aeronomy [SA]
MN: 2005 Joint Assembly