Contribution Contributed Talk
The Kassel Laboratory Astrophysics THz Spectrometers
- Ms. Doris HERBERTH
- Ms. Doris HERBERTH (Universität Kassel)
At the laboratory astrophysics group in Kassel a new broadband fast sweep spectrometer at MW to submm wavelengths has been setup in order to study transient molecules in a supersonic jet. An arbitrary waveform generator (AWG) is used to generate chirped pulses with a linear frequency sweep in the 100 MHz regime and pulse durations of a few microseconds. These pulses are up-converted to the 20-100 GHz frequency range utilizing a synthesizer and a standard amplifier multiplier chain (AMC). NH$_3$ has been measured between 18-26 GHz in a supersonic jet of 500 $\mu$sec duration and Acetonitrile (CH$_3$CN) spectra were recorded in the 90-110 GHz range. The spectrometer is capable of providing fast, broad band and low-noise measurements. Experiments with unstable molecular production conditions can greatly benefit from these advantages. The setup enables the study of Van der Waals-clusters, as well as carbon chain molecules and small metal-containing refractory molecules when combined with appropriate molecular sources. In addition, our THz spectrometers were currently expanded to Doppler-free absorption spectroscopy, which was tested using D$_2$O and HOOD transitions in the 200 GHz region.
We present a brief overview of the THz technology used at the laboratory astrophysics group in Kassel/Germany, including recent projects on fast spectral scanning techniques for molecular jet experiments.