EFFECTS OF O2- AND SF6 VIBRATIONAL-ENERGY ON THE RATE-CONSTANT FOR CHARGE-TRANSFER BETWEEN O2- AND SF6(1)

Rate constants for the charge-transfer reaction of O2- with SF6 have b een measured as a function of the average kinetic energy (KE(cm)) at s everal temperatures in a selected-ion flow-drift tube. Increasing kine tic energy is found generally to decrease the reactivity. In the tempe rature range below 300 K, increasing temperature is found to decrease the rate constants; above 300 K the rate constants increase with tempe rature. Information on the internal energy dependences of the reaction s is derived from the data. The data indicate that neither rotations n or low-frequency vibrations measurably affect the reactivity. Higher-f requency vibrations and/or overtones are found to enhance the reactivi ty greatly, presumably by distorting the geometry of SF6 to match more closely that of SF6-. Vibrations of O2- are found to increase the rea ctivity by a factor of 2.9 at 162 K.