Knowledge Bank

A time-resolved double resonance technique, involving two CO lasers, was used to study various inelastic processes among the rotational levels of CO. The CO lasers transitions ware tuned to the $1\to 0$ band for the PUMP and to the $2\to 1$ band for the PROBE. Gas pressures in the sample cell were in the range 1-100 mtorr. The investigated levels lied from J = 8 to J = 12. Rotational relaxation behaviours were measured when varying pressure, temperature (room or liquide-$N2$), type of perturber ($CO,He,H2$) and the direction of polarization of the laser beams. The results are discussed in connection with the line-broadening available data. Detailed information can be obtained, such as ``collisional selection rules’’, importance of velocity changes or alignment relaxation rate.