Intermolecular vibrations and relaxation dynamics in complexes of OHA(2)Sigma(+) (v'=0,1) with N-2

The intermolecular vibrational energy levels supported by the OH A(2) Sigma(+) (upsilon' = 0,1) + N-2 potentials have been characterized spectroscopically through excitation of OH-N-2 complexes in the OH A (2) Sigma(+)-X(2) Pi 0-0 and 1-0 spectral regions. At least 95 levels correlating with OH A (2) Sigma(+) (upsilon' = 0) + N-2 are observed in fluorescence depletion experiments. OH-N-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-2 laser-induced fluorescence occurs at the OH A(2) Sigma(+) (upsilon' = 0) + N-2 dissociation limit, enabling determination of the ground and excited state binding energies at similar to 250 and greater than or equal to 1372 cm(-1) respectively. In the OH A-X 1-0 region, OH-N-2 transitions originating from a common ground state level to single or groups of intermolecular vibrational levels correlating with OH A(2) Sigma(+) (upsilon' = 1) + N-2 an observed via laser-induced fluorescence and fluorescence depletion measurements. Comparison of the OH-N-2 spectra obtained in the OH A-X 0-0 and 1-0 regions reveals that vibrational excitation of OH A(2) Sigma(+) increases the OH-N-2 binding energy by 139 cm(-1). OH-N-2 complexes excited in the OH A-X 1-0 region undergo ultrafast dynamics (< 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-2 prepared in the intermolecular levels derived from OH A(2) Sigma(+) (upsilon' = 1) + N-2. (C) 1996 American Institute of Physics.