Knowledge Bank

We report on the setup of a supersonic jet spectrometer allowing measurements of rot-vibrational transitions in cold carbon clusters in the frequency range of 1.75 to 1.95 THz. The spectrometer consists of a multi reflection Herriott cell and uses a frequency tripled backward-wave oscillator source. It is the result of the combination of the existing Cologne Supersonic Jet Spectrometer for THz Application (SuJeSTA) with the 1.9 THz portable and stand-alone local oscillator of the German Receiver for Astronomy at Terahertz frequencies (GREAT). Due to the oscillator's frequency stabilization system, a spectral resolution of 13 kHz is achieved. An overview of the functional setup of the spectrometer and first measurements of the Q(10) bending vibration of the $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}$C$3$ carbon cluster at 1935.87 GHz are reported. Ongoing projects for the measurement of submillimeter transitions in the $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}$C$3$ and C$7$ carbon clusters in the accessible terahertz region will be discussed.