Energy transfer in polyatomic molecules. II. Relative catalytic efficiency for energy transfer to different vibrations to the same molecule

Abstract

Vibrations of sulphur dioxide show two separate relaxation times. Values of r 1 = 6.0 × 10 -8 s for the vibrations of 519 cm -1 and r 2 = 1.2 × 10 -6 s for the vibrations of 1151 and 1361 cm -1 have been derived from new ultrasonic measurements, in fair agreement with earlier work. Molecules studied as possible vibration-translation catalysts included ethane, ethylene, water, and n -hexane. No enhanced efficiency of energy transfer was observed with ethylene. Ethane and water molecules were found to be only moderately efficient catalysts; proportionally, they exert a greater effect for processes associated with r 1 . Deuterium oxide is found to be somewhat more efficient than water. n -Hexane is highly efficient for both the r 1 and r 2 relaxation processes of sulphur dioxide. These observations are discussed in relation to various mechanisms for the catalysis of energy transfer.