Knowledge Bank

The infrared spectrum of $OD-N2$ has been obtained in the OD overtone region at $1.9\mu m$ using an IR-UV double resonance technique. An optical parametric oscillator prepares $OD-N2$ with two quanta of OD stretch, while an UV laser operating in the $ODA-X1-2$ region promotes $OD-N2(2\nu OD)$ to the excited A electronic state, resulting in a laser-induced fluorescence signal. A rotationally resolved infrared spectrum of the pure overtone band of $OD-N2$ has been observed at $5174.0cm-1$, shifted $0.7cm-1$ to lower energy than the OD monomer $Q(3/2)$ line. Analysis of the rotational structure reveals a $P=3/2$ projection of the total angular momentum along the intermolecular axis originating from the unquenched electronic angular momentum of OD in a linear $OD-N2$ complex. A lifetime of approximately 140 ns has been measured for $OD-N2(2\nu OD)$ by varying the time delay between the IR and UV lasers. In addition, two combination bands, involving OD stretch and geared bend excitation, have also been identified 35.1 and $40.6cm-1$ to higher energy of the pure overtone band. A surprising decrease in lifetime has been observed upon excitation of one of the combination bands. The $OD-N2$ observations will be compared with previous results for $OH-N2$ to provide detailed information on the anisotropy of the intermolecular potential and the vibrational predissociation mechanism.