15min:

CHRISTA HAASE, JINJUN LIU AND FRÉDÉRIC MERKT, Laboratorium für Physikalische Chemie, ETH-Zürich, 8093 Zürich, Switzerland.

The fundamental bands of the CCl₃ asymmetric deformation modes of selected isotopomers of chloroform (CHCl₃) and freon-11 (CFCl₃) 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 ₆ fundamental transition of ¹²CH³⁵Cl₃ confirmed previously suggested values for C₆ and C_{6 6}. The fundamental frequencies were derived with a precision of 2~GHz for all compounds except CF³⁵Cl₃, where the precision amounted to 3~GHz. The frequencies are in agreement with values calculated 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.