Siegel der Universität

Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut


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Jet Spectroscopy of Weakly Bound Molecular Complexes


The weakly bound complexes and small helium and hydrogen clusters can be efficiently produced in a supersonic jet expansion of a gas mixture into vacuum. The temperature of the sample in the jet expansion is on the order of a few Kelvin, and the complexes are stabilized in this nearly collision-free environment. ...more



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.

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