Collisional excitation of CO2 by N2, O2, and Ar

We have measured cross sections for the T‐V excitation of the asymmetric mode of ground state CO2 molecules in collision with N2, O2, and Ar molecules at relative velocities in the range from 2 to 5 km/s. Excitation was brought about by interacting two slightly collimated molecular beams in the field of view of an InSb photovoltaic detector which monitored resulting radiation in the 4.3 μm band. The excitation cross sections for all three combinations of partners were of similar magnitude and had a strong dependence upon collision velocity. In the case of N2–CO2, for which we have the most data, the measured cross sections range from about 4 × 10−19 cm2 at 2 km/s to about 1 × 10−17 cm2 at 5 km/s.