ROTATIONAL AND VIBRATIONAL-ENERGY TRANSFER IN CH-(B-(2)SIGMA(-))

Rate constants have been obtained for rotational and vibrational energ y transfer within the B ((2) Sigma(-)) state of CH by collisions with Ar and N-2. By using laser photolysis of CHBr3 as the source of CH (B) , it was possible to produce a wide range of rotational and vibrationa l levels (N less than or equal to 15, v less than or equal to 1). The rate constants for rotational relaxation are found to be comparable to gas kinetic (k < 1.8 X 10(-10) cm(3) molecule(-1) s(-1)). At the peak , the rates for vibrational energy transfer are of a similar order of magnitude, particularly for argon. These results, coupled with the obs erved propensity for multiquantum changing collisions for rotational r elaxation, suggest that there is a small attractive interaction betwee n the CH (B) radical and the relaxing gas.