Precision broadband Spectroscopy in the Terahertz Region

Winnewisser, G.; Krupnov, A. F.; Tretyakov, M.Yu.; Liedtke, M.; Lewen, Frank; Saleck, A. H.; Schieder, R.; Shkaev, A. P.; Volokhov, S.V.

doi:10.1006/jmsp.1994.1132

Cited by 123 publications

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“…Individual transitions have been recorded with the Cologne Terahertz Spectrometer (CTS) which has been described in detail by Winnewisser et al (1994). It uses broadband tunable, phase-locked backward-wave oscillators (BWOs) as powerful sources, and a magnetically tuned, liquid helium cooled hotelectron InSb bolometer as detector.…”

Section: Methodsmentioning

confidence: 99%

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Müller¹,

Drouin

Pearson

2009

A&A

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Context. Methyl cyanide is an important trace molecule in star-forming regions. It is one of the more common molecules used to derive kinetic temperatures in such sources. Aims. As preparatory work for Herschel, SOFIA, and in particular ALMA we want to improve the rest frequencies of the main as well as minor isotopologs of methyl cyanide. Methods. The laboratory rotational spectrum of methyl cyanide in natural isotopic composition has been recorded up to 1.63 THz. Results. Transitions with good signal-to-noise ratio could be identified for CH 3 CN, 13 CH 3 CN, CH 13 3 CN, CH 3 C 15 N, CH 2 DCN, and 13 CH 13 3 CN in their ground vibrational states up to about 1.2 THz. The main isotopic species could be identified even in the highest frequency spectral recordings around 1.6 THz. The highest J quantum numbers included in the fit are 64 for 13 CH 13 3 CN and 89 for the main isotopic species. Greatly improved spectroscopic parameters have been obtained by fitting the present data together with previously reported transition frequencies.Conclusions. The present data will be helpful to identify isotopologs of methyl cyanide in the higher frequency bands of instruments such as the recently launched Herschel satellite, the upcoming airplane mission SOFIA or the radio telescope array ALMA.

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Section: Methodsmentioning

confidence: 99%

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Müller¹,

Drouin

Pearson

2009

A&A

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“…For details of the spectrometer see e. g. [4], A 4.4 m long free-space cell of Duran glass was filled with the sample gas of about 3 Pa. The transmission intensity was measured by a liquid-He-cooled InSb detector.…”

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Sub-millimeter Wave Spectra of Cyanoacetylene and Revised Ground State Constants

Yamada

Moravec

Winnewisser

1995

Zeitschrift Für Naturforschung A

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Sixteen new rotational transitions of cyanoacetylene in the ground vibrational state have been measured in the frequency region from 570 GHz to 710 GHz by the Cologne sub-millimeter wave spectrometer. The observed transition frequencies were analyzed together with unpublished millimeter wave data of our group and with the data available in the literature. Precise rota tional constant and the quartic and sextic centrifugal distortion constants have been determined; B = 4549.058224(37) MHz, D = 0.544110(19) kHz, and H = 0.0345(21) mHz.

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“…We have met the Lamb dip requirements in our submillimeterwave laboratory using the backward wave oscillator (BWO)-based spectrometer system described in previous publications [1,2], The high power provided by the BWOs employed is suffi cient at 570 GHz to saturate rotational transitions of ammonia without the use of resonant cavities. The backward-traveling radiation is caused by reflections from various optical surfaces of the spectrometer, and it seems clear that the majority of the reflected power comes from the detector.…”

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“…The BWO is phase-stabilized to a harmonic multiple of a 78-118 GHz synthesizer (Institute of Electronic Measure ment, KVARZ, Nizhnii Novgorod, Russia), generated in a planar Schottky diode harmonic mixer employ ing semi-parabolic optics. The development of these 0932-0784 / 95 / 1200-1 f 9 9 $ 06.00 © -Verlag der Zeitschrift für Naturforschung, D-7202 7 Tübingen components and the phase stabilization electronics is discussed in the recent literature [1,11,12,13]. The resulting radiation is focused through a 3.5 meter ab sorption cell constructed of Pyrex and wedged Teflon windows, and then detected with a liquid heliumcooled InSb hot-electron bolometer (QMC Inst.…”

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Sub-Doppler Spectroscopy of Ammonia Near 570 GHz

Belov

Klaus

Plummer

et al. 1995

Zeitschrift Für Naturforschung A

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We have employed the Cologne terahertz spectrometer [ 1,2] to observe Lamb dip and crossover phenomena in rotational spectra at 572 GHz. Because of the large power output of the backward wave oscillators used in the system, no special means are required to induce this saturation effect; the coincidentally reflected radiation from the bolometer present in our quasi-optical absorption cell is sufficient to saturate the v, = 0 sub-group. This effect has allowed the observation of the three previously unresolved hyperfine components of the l4NH3 A -S, JK = 10 -00 transition, and was also observed for the analogous NH3 transition in natural abundance (i. e. 0.366 %). These measurements indicate a possible improvement of molecular transition frequencies in the submillimeter region.

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Precision broadband Spectroscopy in the Terahertz Region

Cited by 123 publications

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Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Sub-millimeter Wave Spectra of Cyanoacetylene and Revised Ground State Constants

Sub-Doppler Spectroscopy of Ammonia Near 570 GHz

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Precision broadband Spectroscopy in the Terahertz Region

Cited by 123 publications

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Rotational spectra of isotopic species of methyl cyanide, CH3CN, in their ground vibrational states up to terahertz frequencies

Rotational spectra of isotopic species of methyl cyanide, CH3CN, in their ground vibrational states up to terahertz frequencies

Sub-millimeter Wave Spectra of Cyanoacetylene and Revised Ground State Constants

Sub-Doppler Spectroscopy of Ammonia Near 570 GHz

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Product

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Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies

Rotational spectra of isotopic species of methyl cyanide, CH₃CN, in their ground vibrational states up to terahertz frequencies