Molecular-Beam Maser for the Shorter-Millimeter-Wave Region: Spectral Constants of HCN and DCN

DeLucia, Frank C.; Gordy, Walter

doi:10.1103/physrev.187.58

Cited by 132 publications

(32 citation statements)

References 19 publications

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“…Moreover, some strong transitions were recorded with sub-Doppler reswas tested by the HCN spectrum observation which is known from (6). Our measurements demonstrated very good ({0.3 olution by the Lamb-dip observation.…”

Section: Results and Analysismentioning

confidence: 81%

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The High-Precision Millimeter-Wave Spectrum of32SO2,32SO2(ν2), and34SO2

Alekseev

Dyubko²,

Ilyushin

et al. 1996

Journal of Molecular Spectroscopy

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Section: Results and Analysismentioning

confidence: 81%

“…Our measurements demonstrated very good ({0.3 olution by the Lamb-dip observation. That is why most of the transitions have been measured with an accuracy of about kHz) agreement with (6).…”

Section: Results and Analysismentioning

confidence: 90%

The High-Precision Millimeter-Wave Spectrum of32SO2,32SO2(ν2), and34SO2

Alekseev

Dyubko²,

Ilyushin

et al. 1996

Journal of Molecular Spectroscopy

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“…The intensities of the methylenimine signals increased over the temperature range 500-9008C. Moreover, signals due to HCN were also present, [17] weakly at 5008C, but strongly at 9008C. FWW interpreted this in terms of chemical activation of the methylenimine by 89 AE 5 kcal mol À1 arising from the activation energy for denitrogenation of azidomethane [18] ,38 AE 2 kcal mol À1 plus the exothermicity of the reaction ,51 AE 3 kcal mol -1 [19,20] (Eqns 1 and 2 and Fig.…”

Section: Introductionmentioning

confidence: 86%

Chemical Activation in Azide and Nitrene Chemistry: Methyl Azide, Phenyl Azide, Naphthyl Azides, Pyridyl Azides, Benzotriazoles, and Triazolopyridines

Wentrup¹

2013

Aust. J. Chem.

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Chemical activation (the formation of 'hot' molecules due to chemical reactions) is ubiquitous in flash vacuum thermolysis (FVT) reactions, and awareness of this phenomenon is indispensable when designing synthetically useful gas-phase reactions. Chemical activation is particularly prevalent in azide chemistry because the interesting singlet nitrenes are high-energy intermediates, and their reactions are highly exothermic. Consequently, chemical activation is observed in the isomerization of methylnitrene CH 3 N to methylenimine (methanimine) CH 2 ¼NH, facilitating the elimination of hydrogen to form HCN or HNC. Rearrangements of phenylnitrene, 1-and 2-naphthylnitrenes, and 2-, 3-and 4-pyridylnitrenes afford cyanocyclopentadiene, 3-and 2-cyanoindenes, and 2-and 3-cyanopyrroles, all showing the effects of chemical activation by undergoing facile interconversion of isomers. Chemical activation can often be reduced or removed entirely by increasing the pressure, thereby promoting collisional deactivation. Larger molecules having more degrees of freedom are better able to dissipate excess energy; therefore the effects of chemical activation are less pronounced or completely absent in the formation of 3-cyanoindole and 1-cyanobenzimidazoles from 3-and 4-quinolylnitrenes and 4-quinazolinylnitrenes, respectively. In compounds possessing nitro groups, chemical activation can cause the loss of the nitro group at nominal temperatures far below those normally needed to cleave the C-NO 2 bond.

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“…Among the transitions observed in the current survey, 2 = 0 data were taken from de Lucia & Gordy (1969), and for several of the higher excited transitions from de Lucia & Helminger (1977). The H 13 CN entries are mostly based on Fuchs et al (2004) and for 2 = 1 and 2 = 0, respectively.…”

Section: Hydrogen Cyanide Hcnmentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

390

523

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Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims. Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods. We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results. About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm −1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ∼50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare isotopologues of vinyl cyanide, cyanoacetylene, and hydrogen cyanide. We also report the detection of transitions from within twelve new vibrationally or torsionally excited states of known molecules. Absorption features produced by diffuse clouds along the line of sight are detected in transitions with low rotation quantum numbers of many simple molecules and are modeled with ∼30-40 velocity components with typical linewidths of ∼3-5 km s −1 . Conclusions. Although the large number of unidentified lines may still allow future identification of new molecules, we expect most of these lines to belong to vibrationally or torsionally excited states or to rare isotopologues of known molecules for which spectroscopic predictions are currently missing. Significant progress in extending the inventory of complex organic molecules in Sgr B2(N) and deriving tighter constraints on their location, origin, and abundance is expected in the near future thanks to an ongoing spectral line survey at 3 mm with ALMA in its cycles 0 and 1. The present single-dish surve...

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Molecular-Beam Maser for the Shorter-Millimeter-Wave Region: Spectral Constants of HCN and DCN

Cited by 132 publications

References 19 publications

The High-Precision Millimeter-Wave Spectrum of32SO2,32SO2(ν2), and34SO2

The High-Precision Millimeter-Wave Spectrum of32SO2,32SO2(ν2), and34SO2

Chemical Activation in Azide and Nitrene Chemistry: Methyl Azide, Phenyl Azide, Naphthyl Azides, Pyridyl Azides, Benzotriazoles, and Triazolopyridines

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

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