  Two laboratory emission spectrometers have been designed and described
previously. Here, we present a follow-up study with special focus on absolute
intensity calibration of the new SURFER-spectrometer (SUbmillimeter Receiver
For Emission spectroscopy of Rotational transitions), operational between 300
and 400~GHz and mostly coincident with ALMA (Atacama Large
Millimeter/submillimeter Array) Band 7.
  Furthermore, we present a feasibility study to extend the detection
frequencies up to 2~THz. First results have been obtained using the SOFIA
(Stratospheric Observatory for IR Astronomy) upGREAT laboratory setup at the
University of Cologne. Pure rotational spectra of the complex molecule vinyl
cyanide have been obtained and are used to give an estimate on the sensitivity
to record ro-vibrational transitions of molecules with astrophysical importance
at 2~THz.
