RATE CONSTANTS FOR THE RELAXATION OF CH(X(2)PI,NU=1) BY CO AND N-2 ATTEMPERATURES FROM 23 TO 584 K

Rate constants have been determined for the collisional relaxation of CH(X(2) Pi,nu = 1) by CO and N-2 over a wide range of temperatures. Ex periments between 584 and 86 K have been performed in heated and cryog enically cooled cells, and rate constants from 295 to 23 K have been m easured in a CRESU (cinetique de reaction en ecoulement supersonique u niforme) apparatus. In both series of experiments, pulsed laser photol ysis was employed to generate CH radicals and the laser-induced fluore scence technique was used to observe the rate of removal of CH(nu = 1) . Vibrational relaxation is rapid, k(298) = 9.7 x 10(-11) cm(3) molecu le(-1) s(-1) for CO and k(298) = 3.1 x 10(-11) cm(3) molecule(-1) s(-1 ) for N-2, and the dependence of the rate constants on temperature is quite slight but complex. The results suggest that relaxation occurs v ia strongly bound complexes, and the implications of the results for t he interpretation of the reactions between CH radicals and CO and N-2 are discussed.