Infrared spectroscopy of OHH2 entrance channel complexes

The rotationally-resolved infrared spectrum of the ground electronic state of OHH2 has been observed near the OH gn = 2 ← 0 origin by an infrared-ultraviolet fluorescence depletion technique. The experimental spectrum agrees remarkably well with a fully ab initio infrared spectrum originating from the lowest intermolecular level of ortho-H2OH. The lack of measurable homogeneous line broadening in the spectrum indicates that neither vibrational predissociation nor chemical reaction is occurring faster than 45 ps. The magnitudes of the depletions, however, suggest that these processes are taking place on the nanosecond time scale.