Far-Infrared Spectrum of Liquid Water*

The infrared spectra of H2O and D2O in the liquid state at ambient temperature (30°C) have been remapped in the spectral region between 10 and 330 μ. The major features observed were extremely intense absorption bands with maxima at 685 and 505 cm−1 in H2O and D2O, respectively. These major bands are overlapped at the low-frequency ends by much less intense bands producing transmittance minima near 193 and 187 cm−1, respectively. No evidence was obtained for the series of narrow bands recently reported by Stanevich and Yaroslavskii. Extinction coefficients have been determined for the range 170–50 cm−1 and are compared with recent data; present data on linear absorption coefficients for H2O in the range 1500–1100 cm−1 are in fair agreement with the results of previous workers. The influence of temperature variations on the frequencies of infrared bands has been studied for all bands in the region between 4000 and 32 cm−1. Theoretical interpretation of the results is discussed briefly.