The Small Molecule Limit of Infrared Multiphoton Dissociation: Collisional Effects in D2CO

The infrared multiphoton excitation of D2CO was studied by monitoring infrared fluorescence from stretching modes of D2CO following excitation in the bending modes. The dependence of the infrared multiphoton dissociation yield on laser wavelength, on laser power, and on reactant and foreign gas pressures was also studied. Severe bottlenecks to excitation through the first few steps are found. Vibration-to-vibration transfer of a bending quantum from one excited D2CO molecule to another is a crucial step. Collision-induced changes of rotational quantum number must also play an important role.