RAMAN-SCATTERING BY PURE WATER AND SEAWATER

Measurements of the magnitude and spectral distribution of the Raman-s cattering coefficients of pure water (b(rw)) and seawater (b(rs)) are presented. Two independent measurements of the spectral distribution o f the Raman-scattering coefficient of pure water were made for inciden t wavelengths ranging from 250 to 500 nm. These measurements revealed a strong dependence of b(rw) on wavelength that could be represented b y (lambda')(-5.3+/-0.3) relationship, where lambda' is the incident wa velength, or a lambda(-4.6+/-0.3) relationship, where lambda is the Ra man-scattered wavelength, when normalized to units of photons. The cor responding relationships for normalization to energy are (lambda')(-5. 5+/-0.4) and lambda(-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 b(rw) for the 3400-cm(-1) line was found to be (2.7 +/- 0.2) x 10(-4)m(-1) for an incident wavel ength of 488 nm, which is consistent with a number of earlier reports. The difference between the magnitudes of the Raman-scattering coeffic ients for pure water and seawater was statistically insignificant. (C) 1998 Optical Society of America.