Millimetre- and submillimetre-wave laser spectrometer for liquids: power and refractive index spectra of acetonitrile and methyl iodide

A millimetre and submillimetre laser spectrometer for the investigation of the power absorption and refractive index of liquids and solutions is described. General design details of the spectrometer are discussed. The beam geometry throughout the measurement system and a minimisation of multiple internal reflections within the windows of the cell are essential design requirements for determining the optical constants of liquids. Power absorption and refractive index spectra for acetonitrile, methyl iodide and their dilute solutions in cyclohexane are presented.