A tunable far infrared optically pumped laser has been used to measure the reflection <i>R</i> and transmission of liquid water at 25°C. The laser covered the range 8.22–175.7 cm<sup>- 1</sup> with an average spacing between lines of 8 cm<sup>- 1</sup>. The optical data were used to find the complex index of refraction <i>nik</i> with typical errors of 2%. A small peak in n was observed near 55 cm<sup>- 1</sup>. This feature correlates with published Raman data. The values of <i>R</i>, <i>n</i>, <i>k</i>, and the absorption coefficient α are given in graphical and tabular form.
© 1980 Optical Society of America
O. A. Simpson, B. L. Bean, and S. Perkowitz, "Far infrared optical constants of liquid water measured with an optically pumped laser," J. Opt. Soc. Am. 69, 1723-1726 (1979)