Pulsed Terahertz Transmission Spectroscopy of Liquid CHCl3, CCl4, and their Mixtures

Abstract

The frequency-dependent absorption coefficient of CHCl3, CCl4, and their mixtures are measured by pulsed terahertz time domain transmission spectroscopy. The absorbance spectrum for neat CHCl3 is shown to compare well with existing experimental data including coverage of the previously difficult to access 0.3−0.9 THz range. Furthermore, fitted curves to the absorbance spectra of the liquid mixtures, based on mole fraction weighted sums of the absorption coefficients of pure CHCl3 and CCl4, indicate the presence of a bulk dipole reducing mechanism, possibly due to clustering of CHCl3 molecules about CCl4. An algebraic extension of the mole fraction weighted fits allows discrimination between relative strengths of the various bimolecular absorption processes. The integrated absorption coefficient for collisionally induced absorption of CHCl3−CCl4 collisions was found to be less than that for CHCl3−CHCl3 collisions by 2.6 ± 0.4 THz cm-1 (integrated absorption coefficient units). Finally, a new procedure for ...