Terahertz absorption spectra of supercritical CHF/sub 3/

Summary form only given, as follows. In order to investigate rotational, and hindered rotational motions, teraherz (THz) absorption spectra of supercritical CHF/sub 3/ are measured along the isotherm of the reduced temperature T/sub r/ = T/T/sub c/ = 1.02. The spectrometer consists of intense THz radiation (sub-mW) and a polarizing Michelson-interferometer equipped with a Si bolometer. As a light source, the THz radiation is generated by focusing a Ti:sapphire laser onto a InAs placed in a strong magnetic field. As a sample cell, there are two characteristic devices; diamond windows set in the Brewster angle to the incident THz radiation and a variable optical path length from 30 /spl mu/m to 20 mm under high-pressure conditions. Their devices allow us to acquire a fringe-free spectrum without interferences of the THz radiation in sample spacing of the cell and to measure spectra in a wide density range by changing an optical path length.