The near-normal incidence spectral reflectance <i>R</i>(ν) of liquid methane at 98 K has been measured in the infrared in the spectral range 6700-350 cm<sup>-1</sup>. The resulting values of <i>R</i>(ν) have been subjected to Kramers-Kronig phase-shift analysis to provide values of the real <i>n</i>(ν) and imaginary <i>k</i>(ν) parts of the complex index of refraction <i>N</i>(ν) = <i>n</i>(ν) + <i>ik</i>(ν) in the range 4000-400 cm<sup>-1</sup>. The results of the present study are presented in graphical form and in tabular form over this range. The strengths <i>S</i> = ∫<i>k</i>(ν) <i>d</i>ν of the absorption bands are compared with the corresponding bands in gaseous methane. Techniques for using the present results to obtain approximate values of the corresponding optical constants of solid methane are discussed.
© 1978 Optical Society of America
Lary W. Pinkley, P. P. Sethna, and Dudley Williams, "Optical constants of liquid methane in the infrared," J. Opt. Soc. Am. 68, 186-189 (1978)