The millimetre-wave spectrum of dimethylsulfide: internal-rotation and centrifugal-distortion analysis

Vacherand, J. M.; Wlodarczak, G.; Dubrulle, A.; Demaison, J.

doi:10.1139/p87-189

Cited by 15 publications

(13 citation statements)

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“…The spectrometers operate in two different modes: the high resolution mode and scan mode. Since the rotational constants reported in Vacherand et al (1987) possess sufficient accuracy, all spectra could be measured directly in the high resolution mode. All lines are split into doublets due to the Doppler effect; the molecular transition frequency is the center frequency.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, we decided to keep a notation that reflects the Hamiltonian block-diagonalization performed in our code. The energy levels are labeled as AA, AE, EA and EE in (Vacherand et al 1987) and (Niide & Hayashi 2004). The spin-weight statistics AA: EE: AE: EA depend on the parity of K a K c , i.e.…”

Section: Theoretical Modelsmentioning

confidence: 99%

“…The spin-weight statistics AA: EE: AE: EA depend on the parity of K a K c , i.e. 6:16:4:2 for K a K c : ee-oo and 10:16:4:6 for K a K c : eo-oe (Vacherand et al 1987 The XIAM code was first used because of its efficiency to treat molecules containing methyl rotors hindered by relatively high potential barriers. We started with a fit including the millimeter wave transitions from Vacherand et al (1987) to optimize the overall rotational and torsional parameters.…”

Section: Theoretical Modelsmentioning

confidence: 99%

“…The next decade, the ν t = 0 measurements were extended by Vacherand et al (1987) with 98 transitions with 5 J 30 in the millimeter wave range 140−300 GHz. These authors combined their measurements with 85 transitions in the 12−64 GHz region reported in Dreizler & Rudolph (1965) and Demaison et al (1980).…”

Section: Introductionmentioning

confidence: 99%

“…In 2004, Niide and Hayashi assigned 66 rotational transitions with J 5 in the 12−35 GHz spectral range, which belong to the first torsional excited states ν 11 = 1 and ν 15 = 1 (Niide & Hayashi 2004). In most of these previous studies, internal rotation analyses were carried out using the XIAM code or other prior codes (Vacherand et al 1987), providing rotational and torsional parameters for each torsional state. However, several problems occur in these previous works: (i) Certain residuals between calculated and observed line frequencies are as large as 10 MHz in Vacherand et al (1987); (ii) separate fits were performed for each ν t torsional state (Niide & Hayashi 2004), and thus no interactions between different torsional states were taken into account and (iii) the torsional excited state transitions were so weak that only transitions with K a 1 could be unambiguously assigned (Niide & Hayashi 2004).…”

Section: Introductionmentioning

confidence: 99%

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Laboratory microwave, millimeter wave and far-infrared spectra of dimethyl sulfide

Jabri

Van

Nguyen

et al. 2016

A&A

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Context. Dimethyl sulfide, CH 3 SCH 3 (DMS), is a nonrigid, sulfur-containing molecule whose astronomical detection is considered to be possible in the interstellar medium. Very accurate spectroscopic constants were obtained by a laboratory analysis of rotational microwave and millimeter wave spectra, as well as rotation-torsional far-infrared (FIR) spectra, which can be used to predict transition frequencies for a detection in interstellar sources. Aims. This work aims at the experimental study and theoretical analysis of the ground torsional state and ground torsional band ν 15 of DMS in a large spectral range for astrophysical use. Methods. The microwave spectrum was measured in the frequency range 2−40 GHz using two Molecular Beam Fourier Transform MicroWave (MB-FTMW) spectrometers in Aachen, Germany. The millimeter spectrum was recorded in the 50−110 GHz range. The FIR spectrum was measured for the first time at high resolution using the FT spectrometer and the newly built cryogenic cell at the French synchrotron SOLEIL. Results. DMS has two equivalent methyl internal rotors with a barrier height of about 730 cm −1 . We performed a fit, using the XIAM and BELGI-C s -2Tops codes, that contained the new measurements and previous transitions reported in the literature for the ground torsional state ν t = 0 (including the four torsional species AA, AE, EA and EE) and for the ground torsional band ν 15 = 1 ← 0 (including only the AA species). In the microwave region, we analyzed 584 transitions with J ≤ 30 of the ground torsional state ν t = 0 and 18 transitions with J ≤ 5 of the first excited torsional state ν t = 1. In the FIR range, 578 transitions belonging to the torsional band ν 15 = 1 ← 0 with J ≤ 27 were assigned. Totally, 1180 transitions were included in a global fit with 21 accurately determined parameters. These parameters can be used to produce a reliable line-list for an astrophysical detection of DMS.

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Section: Methodsmentioning

confidence: 99%

Section: Theoretical Modelsmentioning

confidence: 99%