Abstract
Quenching of I2* [Formula: see text] (υ′ = 26) is shown to take place to the exclusion of vibrational-energy transfer in iodine at pressures up to 19 mm. A possible quenching mechanism involving sensitized predissociation of the collision partner is described. Vibrational transfer in collisions with H2 and D2 is found to occur at less than every gas kinetic collision. Arguments on general grounds are put forward to support this result, which conflicts with that of earlier workers. Increase in the mass of the isotope is found to bring about increased efficiency of vibrational transfer.