THE MILLIMETER-WAVE SPECTRUM OF METHACROLEIN. TORSION-ROTATION-VIBRATION EFFECTS IN THE EXCITED STATES

2015 ◽  
Author(s):  
Olena Zakharenko ◽  
T. Huet ◽  
Juan-Ramon Aviles Moreno ◽  
R. Motiyenko
Keyword(s):  
Excited States ◽  
Millimeter Wave ◽  
Wave Spectrum

scholarly journals The millimeter-wave spectrum and astronomical search for ethyl methyl sulfide

2020 ◽  
Vol 639 ◽  
pp. A129
Author(s):  
C. Cabezas ◽  
C. Bermúdez ◽  
B. Tercero ◽  
J. Cernicharo
Keyword(s):  
Internal Rotation ◽  
Excited States ◽  
Millimeter Wave ◽  
Wave Spectrum ◽  
Potential Candidate ◽  
Rotational Spectrum ◽  
Methyl Sulfide ◽  
Ethyl Methyl ◽  
Abundant Element ◽  
High Level

Context. Sulfur-containing molecules constitute only 8% of the molecules observed in the interstellar medium (ISM), in spite of the fact that sulfur has been shown to be an abundant element in the ISM. In order to understand the chemical behavior of the ISM and specific cases like the missing sulfur reservoir, a detailed chemical molecular composition in the ISM must be mapped out. Aims. Our goal is to investigate the rotational spectrum of ethyl methyl sulfide, CH3CH2SCH3, which seems to be a potential candidate for observation in the ISM since the simpler analogs, CH3SH and CH3CH2SH, have already been detected. Rotational spectrum of ethyl methyl sulfide has been observed before, but its experimental rotational parameters are not precise enough to allow its detection in the ISM. Methods. The rotational spectrum of ethyl methyl sulfide in the frequency range 72−116.5 GHz was measured using a broadband millimeter-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches and identification of the vibrational excited states of ethyl methyl sulfide was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. Results. The rotational spectra for the trans and gauche conformers of ethyl methyl sulfide was analyzed, and a total of 172 and 259 rotational transitions were observed for each one, respectively. The observation of A − E internal rotation splittings allowed the experimental determination of the V3 hindered internal rotation barrier height for both trans and gauche species. In addition, the vibrational excited states, resulting from the lowest frequency vibrational mode ν30 were identified for both conformers. The new experimental rotational parameters were employed to search for ethyl methyl sulfide in the warm and cold molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and 2 mm.

scholarly journals The millimeter-wave spectrum and astronomical search of succinonitrile and its vibrational excited states

2019 ◽  
Vol 629 ◽  
pp. A35 ◽  
Author(s):  
C. Cabezas ◽  
C. Bermúdez ◽  
J. D. Gallego ◽  
B. Tercero ◽  
J. M. Hernández ◽  
...  
Keyword(s):  
Excited States ◽  
Millimeter Wave ◽  
Dipole Moments ◽  
Saturated Hydrocarbon ◽  
Wave Spectrum ◽  
Rotational Spectrum ◽  
Rotational Spectra ◽  
Quantum Numbers ◽  
Centrifugal Distortion Constants ◽  
High Level

Context. Dinitriles with a saturated hydrocarbon skeleton and a −C≡N group at each end can have large electric dipole moments. Their formation can be related to highly reactive radicals such as CH2CN, C2N, or CN. Thus, these saturated dinitriles are potential candidates to be observed in the interstellar medium (ISM). Aims. Our goal is the investigation of the rotational spectrum of one of the simplest dinitriles N≡C−CH2−CH2−C≡N, succinonitrile, whose actual rotational parameters are not precise enough to allow its detection in the ISM. In addition, the rotational spectra for its vibrational excited states will be analysed. Methods. The rotational spectra of succinonitrile was measured in the frequency range 72−116.5 GHz using a new broadband millimeter-wave spectrometer based on radio astronomy receivers with Fast Fourier Transform backends. The identification of the vibrational excited states of succinonitrile was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. Results. A total of 459 rotational transitions with maximum values of J and Ka quantum numbers 70 and 14, respectively, were measured for the ground vibrational state of succinonitrile. The analysis allowed us to accurately determine the rotational, quartic, and sextic centrifugal distortion constants. Up to eleven vibrational excited states, resulting from the four lowest frequency vibrational modes ν13, ν12, ν24, and ν23 were identified. In addition to the four fundamental modes, we observed overtones together with some combination states. The rotational parameters for the ground state were employed to unsuccessfully search for succinonitrile in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b, and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and the Yebes 40 m at 1.3 cm and 7 mm.

Millimeter-wave spectrum of 4-cyanopyridine in its ground state and lowest-energy vibrationally excited states, ν20 and ν30

2020 ◽  
Vol 369 ◽  
pp. 111274 ◽  
Author(s):  
P. Matisha Dorman ◽  
Brian J. Esselman ◽  
Jieun E. Park ◽  
R. Claude Woods ◽  
Robert J. McMahon
Keyword(s):  
Excited States ◽  
Millimeter Wave ◽  
Ground State ◽  
Wave Spectrum ◽  
Vibrationally Excited

Millimeter-Wave Spectrum of Fluorodiacetylene (HCCCCF)

1999 ◽  
Vol 193 (2) ◽  
pp. 273-276 ◽  
Author(s):  
Toshiaki Okabayashi ◽  
Noriko Yamashita ◽  
Yoshiko Sakai ◽  
Mitsutoshi Tanimoto
Keyword(s):  
Millimeter Wave ◽  
Wave Spectrum

Conformation and Stability of Adducts of Cyclic Ammines with Water:  Free Jet Absorption Millimeter-Wave Spectrum of Pyrrolidine−Water

1998 ◽  
Vol 120 (11) ◽  
pp. 2616-2621 ◽  
Author(s):  
Walther Caminati ◽  
Adele Dell'Erba ◽  
Gianni Maccaferri ◽  
Paolo G. Favero
Keyword(s):  
Millimeter Wave ◽  
Wave Spectrum ◽  
Free Jet
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