Raman-scattering cross sections for water vapor

Abstract

We present cross sections for Raman scattering from water vapor excited at the four argon-laser wavelengths 476.5, 488.0, 496.5, and 514.5 nm. These cross sections, for the strong vibrational band centered at a shift near 3654 cm⁻¹, are approximately 2.5 times larger than the corresponding N₂Q-branch cross sections, and follow closely the expected (1/λ_R)⁴ dependence, where λ_R is the Raman scattering wavelength. We also report observations of the room-temperature depolarization and spectral profile of the band, and the overall spectral distribution of the scattering from 470 to 630 nm, for incident light at 488 nm. The latter observation indicates the absence of any other strong vibrational Raman-active modes.