The rotational spectrum for the lowest vibrational mode for CCl3F has been measured in the 0.1-2 THz frequency range using a compact time-resolved terahertz spectrometer. The peak of the population spectrum for the ground state rotational manifold was observed at 0.3 THz. The observed absorption profile was modeled with rotational and vapor pressure parameters. The limits of detectivity of the compact THz system are discussed in context of atmospheric sensing. (c) 2006 Elsevier B.V. All rights reserved.