Intermolecular vibrations and relaxation dynamics in complexes of OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}{prime}=0,1) with N{sub 2}

Journal Article · Sun Dec 01 04:00:00 EST 1996 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.472732· OSTI ID:401698

Schwartz, R L; Giancarlo, L C; Loomis, R A; Bonn, R T; Lester, M I ^[1]

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1. Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States)

The intermolecular vibrational energy levels supported by the OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}{prime}=0,1)+N{sub 2} potentials have been characterized spectroscopically through excitation of OH{endash}N{sub 2} complexes in the OH {ital A}{sup 2}{Sigma}{sup +}-{ital X}{sup 2}{Pi} 0-0 and 1-0 spectral regions. At least 95 levels correlating with OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}`=0)+N{sub 2} are observed in fluorescence depletion experiments. OH-N{sub 2} complexes prepared in these levels have lifetimes with lower limits ranging from 1.4 to 8 ps due to rapid electronic quenching which precludes their detection by laser-induced fluorescence. An onset of OH-N{sub 2} laser-induced fluorescence occurs at the OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}`=0)+N{sub 2} dissociation limit, enabling determination of the ground and excited state binding energies at {approx}250 and {ge}1372 cm{sup -1}, respectively. In the OH {ital A}-{ital X} 1-0 region, OH-N{sub 2} transitions originating from a common ground state level to single or groups of intermolecular vibrational levels correlating with OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}`=1)+N{sub 2} are observed via laser-induced fluorescence and fluorescence depletion measurements. Comparison of the OH{endash}N{sub 2} spectra obtained in the OH {ital A}-{ital X} 0-0 and 1-0 regions reveals that vibrational excitation of OH {ital A}{sup 2}{Sigma}{sup +} increases the OH-N{sub 2} binding energy by 139 cm{sup -1}. OH-N{sub 2} complexes excited in the OH {ital A}-{ital X} 1-0 region undergo ultrafast dynamics ({lt}200 fs) which give rise to extensive spectral line broadening. A kinetic model indicates that vibrational predissociation is the dominant decay channel for OH-N{sub 2} prepared in the intermolecular levels derived from OH {ital A}{sup 2}{Sigma}{sup +} ({ital v}`=1)+N{sub 2}. {copyright} {ital 1996 American Institute of Physics.}

• OSTI ID: 401698
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 23 Vol. 105; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BINDING ENERGY
FLUORESCENCE SPECTROSCOPY
HYDROXYL RADICALS
INTERMOLECULAR FORCES
LASER RADIATION
LINE BROADENING
MOLECULE-MOLECULE COLLISIONS
NITROGEN
NITROGEN MOLECULES
POTENTIAL ENERGY SURFACES
PREDISSOCIATION
RELAXATION TIME
VIBRATIONAL STATES