VIBRATIONAL SPECTRA OF CHLOROFORM, FREON-11 AND SELECTED ISOTOPOMERS IN THE TERAHERTZ REGION

Author Institution: Laboratorium fur Physikalische Chemie, ETH-Zurich, 8093 Zurich, SwitzerlandThe fundamental bands of the CCl$_3$ asymmetric deformation modes of selected isotopomers of chloroform (CHCl$_3$) and freon-11 (CFCl$_3$) have been measured between 7 and 8~THz in a static cell at ambient temperature using a laser-based source of tunable radiation in the terahertz region (0.1-10~THz) of the electromagnetic spectrum. Simulation of the rotational contour of the $\nu_6$ fundamental transition of $^{12}$CH$^{35}$Cl$_3$ confirmed previously suggested values for $C_6$ and $C_6\zeta_6$. nderline{\textbf{170}}, 215, (1995).} The fundamental frequencies were derived with a precision of 2~GHz for all compounds except CF$^{35}$Cl$_3$, where the precision amounted to 3~GHz. The frequencies are in agreement with values calculated \textit{ab initio}. Extension of the experimental setup to enable measurement of THz spectra of molecules in supersonic jet expansions and partially resolve their rotational structure is in progress