Far infrared optical constants of liquid water measured with an optically pumped laser

Abstract

A tunable far infrared optically pumped laser has been used to measure the reflection R and transmission of liquid water at 25°C. The laser covered the range 8.22–175.7 cm−1 with an average spacing between lines of 8 cm−1. The optical data were used to find the complex index of refraction n-ik with typical errors of 2%. A small peak in n was observed near 55 cm−1. This feature correlates with published Raman data. The values of R, n, k, and the absorption coefficient α are given in graphical and tabular form.