Shockhyphen;Tube Study of Vibrational Relaxation in Carbon Monoxide for the Fundamental and First Overtone

摘要

The rate of vibrational excitation in rapidly heated CO has been determined for the temperature range 1100deg;mdash;2500deg;K by observation of infrared emission behind incident shocks. Great care was taken to eliminate impurity effects. The data agree to within 15 with those of Matthews. Separate observations of fundamental and overtone emission demonstrated that excitation occurs in a stepwise fashion. Collisional population of thev=2 level by successive single quantum transition is at least ten times faster than the direct 0rarr;2 excitation process. Vibrational relaxation times of CO were determined for the pure gas and for the mixtures; 5 COmdash;95 Ar, 5 COmdash;95 N2, and 99 COmdash;1 H2. At 2000deg;K, tgr;(COsngbnd;CO) = 60 mgr;sec, tgr;(COsngbnd;Ar) = 350 mgr;sec, tgr;(COsngbnd;N2) = 640 mgr;sec, tgr;(COsngbnd;H2) = 0.7 mgr;sec, all for one atmosphere total pressure with the CO infinitely dilute in the secondhyphen;named gas. The differences found between COsngbnd;CO collisions and COsngbnd;N2collisions with respect to vibrational excitation are not explained by current theories.