Electronic spectroscopy and quenching dynamics of OH{endash}H{sub 2}/D{sub 2} pre-reactive complexes
- Department of Chemistry, University of Pennsylvania Philadelphia, Pennsylvania 19104-6323 (United States)
Binary complexes of OH {ital X}{sup 2}{Pi} and H{sub 2}/D{sub 2} have been stabilized in the entrance valley to the hydrogen abstraction reaction and identified in the OH {ital A}{sup 2}{Sigma}{sup +}{endash}{ital X}{sup 2}{Pi} 0{endash}0 spectra region. Nearly all of the intermolecular vibrational levels supported by the OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}{prime}=0)+H{sub 2}/D{sub 2} potential energy surface have been observed in fluorescence depletion experiments. Rapid electronic quenching precludes the observation of OH{endash}H{sub 2}/D{sub 2} prepared in these levels by laser-induced fluorescence. A sharp onset of laser-induced fluorescence occurs at the OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}{prime}=0)+H{sub 2}/D{sub 2} dissociation limit. The binding energies for OH{endash}H{sub 2}/D{sub 2} in the ground state correlating with OH {ital X}{sup 2}{Pi} ({ital v}{double_prime}=0)+H{sub 2}/D{sub 2} have been determined to be 54 cm{sup {minus}1} and more than 66 cm{sup {minus}1}, respectively. The OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}{prime}=0)+H{sub 2}/D{sub 2} excited state is found to be at least 577 cm{sup {minus}1} (H{sub 2}) and 639 cm{sup {minus}1} (D{sub 2}) more strongly bound than the ground state. The positions of observed features are compared with the corresponding intermolecular levels observed by laser-induced fluorescence in the OH {ital A}{endash}{ital X} 1{endash}0 region as well as theoretical predictions of the transition energies based on {ital ab} {ital initio} potentials for the ground and excited electronic states. The OH{endash}H{sub 2}/D{sub 2} intermolecular levels correlating with OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}{prime}=0)+H{sub 2}/D{sub 2} have lifetimes of 3.2{endash}4.5 ps, deduced from homogeneous linewidths, due to quenching and/or chemical reaction. {copyright} {ital 1996 American Institute of Physics.}
- OSTI ID:
- 434615
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 18 Vol. 104; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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