PRECISION BROADBAND SPECTROSCOPY IN THE TETRAHERTZ REGION
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Date
1994
Journal Title
Journal ISSN
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Publisher
Ohio State University
Abstract
For the first time precision broadband spectroscopic measurements have been performed in the spectral region up to 1.1 THz. Continuous frequencies coverage and microwave accuracy are achieved by employing frequency and phase stabilized Backward Wave Oscillators (BWOs). This breakthrough in high-resolution scanning spectroscopy became possible by the opening of the borders between East and West and essentially by the collaborative efforts between Cologne University, Germany, and the Institute of Applied Physics, Nizhnii Novgorod, $Russia.^{a}$ Extensive measurements have been performed on HSSH, HOOH, their various isotopomers, and astrophysically relevant molecules and radicals. Some of their spectra will be presented. We have performed extensive measurements of the $^{r}Q_{Ka}$ branches for $K_{a}\geq 2$ of HSSH and its various isotopomers for two purposes: (i) to obtain new spectroscopic information concerning the anomalous K-doubling and the mass dependence of the torsional problem and (ii) to demonstrate the hitherto unknown wide tunability of the employed BWO’s and the high sensitivity of the new Cologne terabertz spectrometer. The essential components of the Cologne spectrometer $system^{b}$ consist of the BWO’s supplied by the ISTOK Research and Production Company (Fryazino, Moscow region), a newly designed multiplier-mixer with low noise HEMT amplifier, two millimeter-wave synthesizers (78 to 118 GHz; 118-178 GHz from the Institute of Electronic Measurement, KVARZ Nizhnii Novgorod), and a He-cooled InSb detector.
Description
$^{a}$M. Liedtke et al., J. Mol. Sectrosc. 161, 317-321 (1993). $^{b}$G. Winnerwisser et al., J. Mol. Spectrosc. 165, 294-300 (1994).
Author Institution: Physikalisches Institut, Universitaet zu Koeln, D-50937 Koeln; Microwave Spectroscopy Laboratory, Applied Physics Institute
Author Institution: Physikalisches Institut, Universitaet zu Koeln, D-50937 Koeln; Microwave Spectroscopy Laboratory, Applied Physics Institute