Siegel der Universität

Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut


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Responsible person

  • surin


The OROTRON spectrometer has become the most sensitive and probably the most powerful tool for investigating inherently extremely weak spectral features of molecular complexes and small clusters in the millimeter-wave (MMW) range [L.A. Surin, Sci. Instrum., 72, 2535 (2001)].

The key element of the spectrometer is a tunable OROTRON oscillator, which generates the radiation (2-3 mm) through the interaction of an electron beam with the electromagnetic field of an open Fabry-Perot resonant cavity. The supersonic molecular jet enters into the resonator perpendicularly to its axis. A high quality factor (Q ≈ 104) of the cavity results in 100 effective passes of the radiation through the jet. Absorption in the cavity causes changes of the electron current in the collector circuit and is detected by measuring these current changes. ...more


Experimental setup of the OROTRON spectrometer.
Recording of the a-type J = 1–0 transition in the He8–C18O cluster by the double resonance method using the OROTRON spectrometer.
Recording of the R(1) transition of the ortho-NH3-ortho-H2 van der Waals complex by the double resonance method using the OROTRON spectrometer.