RAYLEIGH SCATTERING OF RUBY LASER LIGHT IN NEUTRAL GASES

Measurements are described of Rayleigh scattering from atoms and molecules in the gaseous state at one atmosphere. The use of a Q-switched ruby laser of 8 MW average power and care in minimizing spurious light permitted the determination of very small depolarizations. In agreement with theoretical predictions, the depolarization ratio for linearly polarized light or argon was found to be vanishingly small. Similarly, for helium. However, xenon and methane exhibited nonzero depolarization ratios. It is found that departures from ideal gas behavior provide the most plausible explanation for these findings. Calculations from currently available theory are presented to support this assertion. The effect of nuclear spin in xenon-129 is considered and shown to contribute negligibly to the measured depolarization. Depolarization ratios were also measured in hydrogen, deuterium, nitrogen, and nitrous oxide, and found to be lower than generally accepted values.