A state-selected study of the ion{endash}molecule reactions O{sup +}({sup 2}D,{sup 2}P)+H{sub 2}O
- Ames Laboratory, USDOE and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)
State-selected absolute cross sections for H{sub 2}O{sup +} and OH{sup +} formed by the O{sup +}({sup 2}D,{sup 2}P)+H{sub 2}O reactions have been measured in the center-of-mass collision energy (E{sub c.m.}) range of {approx}0.10{endash}30 eV. The charge transfer cross sections for O{sup +}({sup 2}D)+H{sub 2}O are significantly higher than those for O{sup +}({sup 4}S)+H{sub 2}O. This observation is attributed to the increased number of accessible exothermic product channels for O{sup +}({sup 2}D)+H{sub 2}O. While the H{sub 2}O{sup +} cross sections for O{sup +}({sup 2}P)+H{sub 2}O are comparable to those from O{sup +}({sup 4}S)+H{sub 2}O at E{sub c.m.}{ge}1 eV, the H{sub 2}O{sup +} cross sections for O{sup +}({sup 2}P)+H{sub 2}O at E{sub c.m.}{lt}1 eV are substantially lower than those for O{sup +}({sup 4}S)+H{sub 2}O. The lower H{sub 2}O{sup +} cross sections observed for O{sup +}({sup 2}P)+H{sub 2}O are rationalized as due to further dissociation of excited charge transfer H{sub 2}O{sup +} ions and/or the efficient competition of the OH{sup +}+OH product channel. The cross sections for OH{sup +} from O{sup +}({sup 2}D,{sup 2}P)+H{sub 2}O are significantly greater than those from O{sup +}({sup 4}S)+H{sub 2}O. The majority of OH{sup +} ions from O{sup +}({sup 2}D,{sup 2}P)+H{sub 2}O are associated with exothermic channels corresponding to the formation OH{sup +}(X{sup 3}{Sigma}{sup {minus}},{sup 1}{Delta},A{sup 3}{Pi})+OH. The comparison of the sum ({sigma}{sub T}) of the cross sections for H{sub 2}O{sup +} and OH{sup +} from O{sup +}({sup 4}S)+H{sub 2}O to those from O{sup +}({sup 2}D)+H{sub 2}O and O{sup +}({sup 2}P)+H{sub 2}O shows that {sigma}{sub T}{close_quote}s for O{sup +}({sup 4}S)+H{sub 2}O and O{sup +}({sup 2}P)+H{sub 2}O are comparable, whereas the {sigma}{sub T} values for O{sup +}({sup 2}D)+H{sub 2}O are greater than those for O{sup +}({sup 4}S)+H{sub 2}O and O{sup +}({sup 2}P)+H{sub 2}O. (Abstract Truncated)
- OSTI ID:
- 435126
- Journal Information:
- Journal of Chemical Physics, Vol. 106, Issue 3; Other Information: PBD: Jan 1997
- Country of Publication:
- United States
- Language:
- English
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