VIBRATIONAL RELAXATION OF SHOCK-HEATED CL2 - EFFECTS OF CO, HCL, AND DCL

The vibrational relaxation of pure Cl2 in the temperature range 400-1400°K, and of binary mixtures of Cl2 with CO, HCl, and DCl in the range 400-1100°K has been studied behind incident shock waves by time-resolved measurement of the postshock density gradient using a laser-beam deflection technique. Results obtained for pure Cl2 are more precise than those previously available at these temperatures, and are in excellent agreement with lower-temperature ultrasonic data. The effect of CO relative to Cl2 is found to be much less than indicated by previous data, and is attributed solely to the lower Cl2-CO reduced collision mass. The effects of HCl and DCl are large, particularly at low temperatures, e.g., HCl is ≈100 times more effective than Cl2 at 400°K. HCl is ≈2-4 times more effective than DCl, depending on the temperature The relative efficiencies are interpreted as a strong indication of rotational effects.