Rotational relaxation time in CO free jets

The electron beam fluorescence technique was applied to measure the rotational energy relaxation cross-sections in carbon monoxide free jets. The data were obtained in the low temperature region from 20 to 200 K and compared with the results of ultrasound, thermal conductivity, free jet and line broadening experiments. The overall scatter of the experimental data runs to one order of magnitude, and their temperature dependence differs. This fact calls for further theoretical and experimental investigations of rotational relaxation rates in carbon monoxide.