Raman scattering by pure water and seawater

Measurements of the magnitude and spectral distribution of the Raman-scattering coefficients of pure water (brw) and seawater (brs) are presented. Two independent measurements of the spectral distribution of the Raman-scattering coefficient of pure water were made for incident wavelengths ranging from 250 to 500 nm. These measurements revealed a strong dependence of brw on wavelength that could be represented by a (λ′)-5.3±0.3 relationship, where λ′ is the incident wavelength, or a λ-4.6±0.3 relationship, where λ is the Raman-scattered wavelength, when normalized to units of photons. The corresponding relationships for normalization to energy are (λ′)-5.5±0.4 and λ-4.8±0.3, respectively. These relationships are found to be consistent with resonance Raman theory for an absorption wavelength of 130 nm. The absolute value of brw for the 3400-cm-1 line was found to be (2.7 ± 0.2) × 10-4 m-1 for an incident wavelength of 488 nm, which is consistent with a number of earlier reports. The difference between the magnitudes of the Raman-scattering coefficients for pure water and seawater was statistically insignificant.