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14 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Laboratory detection of the C3N an C4H free radicals

The millimeter-wave spectra of the linear carbon chain free radicals C3N and C4H, first identified in IRC + 10216 and hitherto observed only in a few astronomical sources, have been detected with a Zeeman-modulated spectrometer in laboratory glow discharges through low pressure flowing mixtures of N2 + HC3N and He + HCCH, respectively. Four successive rotational transitions between 168 and 198 GHz have been measured for C3N, and five rotational transitions between 143 and 200 GHz for C4H; each is a well-resolved spin doublet owing to the unpaired electron present in both species. Precise values for the rotational, centrifugal distortion, and spin doubling constants have been obtained, which, with hyperfine constants derived from observations of the lower rotational transitions in the astronomical source TMC 1, allow all the rotational transitions of C3N and C4H at frequencies less than 300 GHz to be calculated to an absolute accuracy exceeding 1 ppm.

Gottlieb, C. A.↗
DOE OSTI2020

Materials Data on C3N by Materials Project

C3N is alpha-like structured and crystallizes in the cubic P2_13 space group. The structure is zero-dimensional and consists of four trimethylamine molecules. C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.39 Å. N3- is bonded in a trigonal planar geometry to three equivalent C1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C3N by Materials Project

C3N is alpha Rhenium trioxide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. C1+ is bonded in a linear geometry to two equivalent N3- atoms. Both C–N bond lengths are 1.66 Å. N3- is bonded to six equivalent C1+ atoms to form corner-sharing NC6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C3N by Materials Project

C3N is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of four methane molecules and one C2N framework. In the C2N framework, C1+ is bonded to four equivalent N3- atoms to form a mixture of corner and edge-sharing CN4 tetrahedra. All C–N bond lengths are 2.07 Å. N3- is bonded in a body-centered cubic geometry to eight equivalent C1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C3N by Materials Project

C3N is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. C1+ is bonded in a square co-planar geometry to four equivalent N3- atoms. All C–N bond lengths are 2.20 Å. N3- is bonded to twelve equivalent C1+ atoms to form a mixture of corner and face-sharing NC12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C3N by Materials Project

C3N crystallizes in the orthorhombic Amm2 space group. The structure is one-dimensional and consists of two ethyne molecules and two CN ribbons oriented in the (0, 0, 1) direction. In each CN ribbon, C1+ is bonded in a linear geometry to two equivalent N3- atoms. Both C–N bond lengths are 1.20 Å. N3- is bonded in a linear geometry to two equivalent C1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C3N by Materials Project

C3N is BCT5 structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four ethanamine, n-methylene- molecules. there are three inequivalent C1+ sites. In the first C1+ site, C1+ is bonded in a distorted single-bond geometry to one C1+ atom. The C–C bond length is 1.35 Å. In the second C1+ site, C1+ is bonded in a single-bond geometry to one C1+ and one N3- atom. The C–N bond length is 1.22 Å. In the third C1+ site, C1+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.33 Å. N3- is bonded in a bent 150 degrees geometry to two C1+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1977

Theoretical study of the butadiynyl and cyanoethynyl radicals - Support for the identification of C3N in IRC + 10216

Quantum-mechanical calculations, using the matrix Hartree-Fock model, have been performed for the butadiynyl and cyanoethynyl radicals. A rotation constant of 4753 MHz is calculated for C4H, while for C3N the value 4955 MHz is obtained. These may be compared with the rotation constant of 4947.5 MHz derived from the recently observed doublets in the millimeter-wave spectrum of IRC + 10216, suggesting the cyanoethynyl radical as the carrier species of these lines. The electric dipole moment and hyperfine coupling constants of both species are predicted.

Wilson, S.↗
NASA NTRS1993

The formation of cyanopolyyne molecules in IRC + 10216

Molecule formation in the outer envelope of the carbon-rich star IRC + 10216 is investigated, with special emphasis on the chemistry of the cyanopolyynes HC(i)N (i = 3, 5, 7). Basic elements of the photochemical model of Glassgold et al. (1986) are revised. A dust model suitable to IRC + 10216 is used for which the extinction properties in the far-UV are those of 500 A amorphous carbon particles. A new chemical route to the formation of large cyanopolyynes is proposed, based on reactions of the radicals C3N and C5N with acetylene, and shown to be efficient. Our results agree qualitatively with observations of the spatial distributions of HCN, CN, HC3N, and C3N, but the calculated column densities of the higher-order cyanopolyynes appear to be too small. The amount of the allenic radical HC2N produced by molecular ion reactions with atomic N agrees with recent observations.

Cherchneff, Isabelle↗
DOE OSTI2022

Orbital engineering of C 3 N monolayer to design efficient synergistic sites electrocatalyst for boosting alkaline hydrogen evolution

Alkaline water electrolyzer (AWE) is one of the promising technologies for hydrogen production at the industrial level. However, energetic inefficiency and low current density impede the development of AWE. Compared with acidic conditions, the Volmer step in alkaline hydrogen evolution reaction (HER) involves extra water dissociation, whose barrier is one of the most vital reasons for the sluggish kinetics of alkaline HER. Herein, choosing C 3 N monolayer as an ideal theoretical model, we design several empty orbitals through intentional metal doping, and further construct synergistic sites on the C 3 N monolayer to accelerate both water dissociation and hydrogen adsorption for alkaline HER. Furthermore, the as-designed Be-doped and Cr-doped C 3 N monolayers exhibit rather low theoretical overpotential of 0.476 eV and 0.216 eV for alkaline HER, respectively, which are even lower than Pt (1 1 1) surface. Moreover, by comparing the water dissociation behaviors on metal-doped C3N monolayer, we find that the empty orbitals with suitable orientation and energy level are useful for promoting the water dissociation process, indicating that we can use orbital engineering strategy to regulate the adsorption strength between adsorbate and surface site. Consequently, it is reasonable to suggest that our orbital engineering strategy would significantly benefit the design of highly efficient alkaline HER electrocatalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1978

Detection of the C4H radical toward IRC plus 10216

Four emission doublets in the millimeter-wave spectrum of IRC plus 10216 are identified as successive rotational transitions of the linear butadiynyl radical (C4H). The identifications are made on the basis of the agreement to within about 1 part in 1000 between the observed rotation constant of C4H and the value obtained from a Hartree-Fock calculation. A rough estimate of the amounts of C4H and C3N in the molecular envelope of IRC plus 10216 is given. The results indicate that C4H seems to be the more abundant species by about a factor of 4.

Guelin, M.↗
NASA NTRS1979

Interstellar synthesis of the cyanopolyynes and related molecules

The cyanopolyynes HC2CN, HC4CN, HC6CN, and HC8CN, and the molecules CH3CHCN and CH3CH2CN, have recently been detected in the interstellar medium. It is shown that the observed abundances of these molecules can be obtained by gas-phase formation pathways if the reaction of H2CN(+) with C2H2 is rapid at low interstellar temperatures. The molecules CH2CHCN and C3N may be formed also by the reactions of H2CN(+) with C2H2, and CH3CH2CN may be formed by reaction of H2CN(+) with C2H4.

Mitchell, G. F.↗
NASA NTRS1991

Is interstellar detection of higher members of the linear radicals CnCH and CnN feasible?

Rotational constants and dipole moments for linear-chain radicals CnCH and CnN are estimated using a combinatiaon of ab initio molecular orbital calculations and observed data on the starting members of the series. CnCH with n = 0-5 have been observed by radioastronomy in carbon-rich interstellar clouds; higher members of the series have 2Pi ground states with large dipole moments and are strong candidates for observation. CN and C3N have also been observed by radioastronomy; higher members of the series, with the possible exception of C5N, have 2Pi ground states with near-zero dipole moments making their interstellar detection hopeless under present observational conditions. C5N can be a strong candidate only if it has a 2Sigma ground state, and best computations so far indicate that this is not the case.

Pauzat, F.↗
NASA NTRS2002

Laboratory Anion Chemistry: Implications for the DIBs, and a Potential Formation Mechanism for a Known Interstellar Molecule

Due to recent interest in molecular anions as possible interstellar species, we have carried out several laboratory studies of anion chemistry. The reactions of the series C(sub n)(sup -); and C(sub n)H(sup -) with H and H2 were studied to address the viability of such species in the diffuse interstellar medium and to address their ability to be carriers of the diffuse interstellar bands (DIBs). These same molecules were also reacted with N and O to show possible heteroatomic products. C(sub m)N(sup - was a particularly stable product from the reaction of C(sub n)(sup -) + N. C3N(sup -) was further reacted with H to study chemistry that could produce HC3N, a known interstellar species. The reactions were done in a flowing afterglow selected ion flow tube apparatus (FA-SIFT). The anions were generated in an electron impact or cold cathode discharge source and the anion of interest was then selected by a quadrupole mass filter. The selected ion was then reacted with the atomic or molecular species in the flow tube and products were detected by another quadrupole. While the C(sub n)(sup -) species do not appear to be viable DIB carriers, their possible presence could provide a mechanism for the formation of known heteroatomic neutral molecules detected in the interstellar medium (ISM).

Eichelberger, B.↗