# INFRARED ACTION SPECTROSCOPY AND TIME-RESOLVED DYNAMICS OF THE OD-CO REACTANT COMPLEX

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 Title: INFRARED ACTION SPECTROSCOPY AND TIME-RESOLVED DYNAMICS OF THE OD-CO REACTANT COMPLEX Creators: Pollack, Ilana B.; Tsiouris, Maria; Leung, Helen O.; Lester, Marsha I. Issue Date: 2002 Publisher: Ohio State University Abstract: Infrared action spectra of the linear OD-CO reactant complex have been recorded in the OD overtone region near $1.9 \mu$m using an infrared pump-ultraviolet probe technique. The pure overtone band of OD-CO $(2\nu_{OD}$) was observed at $5148.4 cm^{-1}$, and combination bands involving the simultaneous excitation of OD stretch and D-atom bend were identified 200.7 and $232.1 cm^{-1}$ to higher energy. Band assignments and spectroscopic constants have been derived from the rotationally resolved structure of the spectra. Direct time-domain measurements yielded a lifetime of 34 ns for OD-CO $(2\nu_{OD})$ prior to decay via inelastic scattering or chemical reaction. This is significantly longer than the laser-limited lifetime of $\leq 5$ ns observed for OH-CO $(2\nu_{OH})$, and is attributed to the closing of a near resonant vibrational energy transfer channel upon deuteration. Intermolecular bending excitation, which drives the structural transformation from the reactant complex to the transition state for reaction, results in a dramatic shortening of the lifetime to $\leq 5$ ns. Excitation of the D-atom bend also supplies sufficient energy to reopen the near resonant vibrational energy transfer channel. Finally, an OD-CO binding energy of $D_{0} \leq 500 cm^{-1}$ has been established from the OD (v=1) product state distribution observed following infrared overtone excitation. Description: $^{a}$On sabbatical leave from Department of Chemistry, Mount Holyoke College, South Hadley, Massachusetts 01075-6407 Author Institution: Department of Chemistry, University of Pennsylvania URI: http://hdl.handle.net/1811/20418 Other Identifiers: 2002-MJ-02