Rayleigh Scattering of Ruby-Laser Light by Neutral Gases*

Abstract

Measurements of Rayleigh scattering from atoms and molecules in the gaseous state at 1-atm pressure are described. 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. No depolarization could be detected in the scattering from argon and helium. However, finite depolarization ratios ρ_ν (for vertically polarized incident light) were measured for xenon and methane: 1.55(±0.25) × 10⁻⁴ and 1.27 (±0.23) × 10⁻⁴, respectively. Departures from ideal-gas behavior provide the most plausible explanation for these findings.