Optical properties of water in the near infrared*

The real n (ν) and imaginary k (ν) parts of the complex refractive index Nˆ = n + i k of water at 27 °C have been determined from measurements of spectral reflectance at near-normal incidence and from measurements of the transmittance of water in carefully constructed absorption cells. Values of n (ν) are reported in graphical and tabular form for the spectral region 3800–27 800 cm−1; values of the Lambert absorption coefficient α(ν) are presented graphically and in tabular form, along with k (ν) for the region 3800–14 500 cm−1. Upper limits of k (ν) are established for the region 14 500–27 800 cm−1. The results are compared with earlier studies.