Mainz 2017 – scientific programme
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MO: Fachverband Molekülphysik
MO 9: Posters 1: Dichroism, VUV and Xray, Clusters, and Cold Molecules
MO 9.18: Poster
Tuesday, March 7, 2017, 17:00–19:00, P OG1
Spectroscopy on cold molecules using a chirped pulse microwave spectrometer — •Pascal Stahl1, Thomas Giesen1, Guido Fuchs1, and Johanna Chantzos2 — 1Institut für Physik, Universität Kassel, 34132 Kassel, Germany — 2Max-Planck-Institut für extraterrestrische Physik, 85741 Garching bei München, Germany
We present a novel technique to investigate molecules in the gas phase in the K- and W-band. The new experimental setup comprises an absorption spectrometer in combination with a supersonic jet.
The purpose of the setup is to detect short-living and small molecules at low temperatures. For this a twin-channel arbitrary waveform generator (AWG) with 400 MS/s sample rate and 145 MHz analog bandwidth emits a (linear) chirp both in phase and as quadrature signal (I/Q-signal). Using a single sideband upconverter this signal is mixed with a carrier signal in the GHz regime that has been produced by a synthesizer. The resulting (mixed) signal is amplified and sent into a coaxial waveguide adapter and horn antenna to be broadcasted into a vacuum chamber. There the radiation interacts with molecules and in case of an absorption the reduced signal is detected via a horn-antenna-detector device (zero bias shottky diode). The signal is then digitized and sent to a computer.
We have measured ammonia, nitrous oxide as well as acetonitrile. In combinaton with a discharge nozzle the spectrometer allows to produce and detect a variety of volatile molecules that are of astrophysical and astrochemical interest.