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Douglas KM, Li LHD, Walsh C, Lehman JH, Blitz MA, Heard DE. Experimental, theoretical, and astrochemical modelling investigation of the gas-phase reaction between the amidogen radical (NH 2) and acetaldehyde (CH 3CHO) at low temperatures. Faraday Discuss 2023; 245:261-283. [PMID: 37340790 DOI: 10.1039/d3fd00046j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
The first experimental study of the low-temperature kinetics of the gas-phase reaction of NH2 with acetaldehyde (CH3CHO) has been performed. Experiments were carried out using laser-flash photolysis and laser-induced fluorescence spectroscopy to create and monitor the temporal decay of NH2 in the presence of CH3CHO. Low temperatures relevant to the interstellar medium were achieved using a pulsed Laval nozzle expansion. Rate coefficients were measured over the temperature and pressure range of 29-107 K and 1.4-28.2 × 1016 molecules per cm3, with the reaction exhibiting a negative temperature dependence and a positive pressure dependence. The yield of CH3CO from the reaction has also been determined at 67.1 and 35.0 K, by observing OH produced from the reaction of CH3CO with added O2. Ab initio calculations of the potential energy surface (PES) were combined with Rice-Rampsberger-Kessel-Marcus (RRKM) calculations to predict rate coefficients and branching ratios over a broad range of temperatures and pressures. The calculated rate coefficients were shown to be sensitive to the calculated density of states of the stationary points, which in turn are sensitive to the inclusion of hindered rotor potentials for several of the vibrational frequencies. The experimentally determined rate coefficients and yields have been used to fit the calculated PES, from which low-pressure limiting rate coefficients relevant to the ISM were determined. These have been included in a single-point dark cloud astrochemical model, in which the reaction is shown to be a potential source of gas-phase CH3CO radicals under dark cloud conditions.
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Affiliation(s)
- Kevin M Douglas
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
| | | | - Catherine Walsh
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
| | - Julia H Lehman
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Mark A Blitz
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
- National Centre for Atmospheric Science (NCAS), University of Leeds, Leeds, LS2 9JT, UK
| | - Dwayne E Heard
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
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2
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Lam CS, Lau KC. Thermochemical Trends in Carbon Chain Molecules HC 2kH/HC 2k-1H ( k = 1-6) Studied by Explicitly Correlated CCSD(T)-F12b Composite Methods. J Phys Chem A 2021; 125:5385-5396. [PMID: 34121392 DOI: 10.1021/acs.jpca.1c03428] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a composite procedure based on explicitly correlated CCSD(T)-F12 calculations for accurate energetic predictions for carbon chain molecules HCnH encompassing both the even (HC2kH) and odd series (HC2k-1H), with the shorter members playing a key role in the evolution of cosmic carbon compounds in both circumstellar envelopes and interstellar medium. This approach considers the contributions of core-valence correlation, scalar relativistic effect, spin-orbit coupling, and zero-point vibrational energy in an additive manner. The computed ionization energies demonstrate outstanding agreement (±0.07 eV) up to a chain size of k = 6 and the literature heats of formation for k ≤ 2 are reproduced with "chemical accuracy" of 1 kcal mol-1. Among the various corrections included, the importance of core-valence correlation effect has been highlighted in the thermochemical calculations for carbon chain growth. The thermochemical trend toward infinite length is also highlighted by extrapolation of ionization energy and triplet-singlet splitting at the CCSD(T) level for k up to 15. The correlation between the end-group effect and the even-odd parity effect observed for HCnH chains has been established with the aid of intrinsic bond orbital localization.
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Affiliation(s)
- Chow-Shing Lam
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong
| | - Kai-Chung Lau
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong
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3
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Cernicharo J, Cabezas C, Endo Y, Agúndez M, Tercero B, Pardo JR, Marcelino N, de Vicente P. The sulphur saga in TMC-1: Discovery of HCSCN and HCSCCH. ASTRONOMY AND ASTROPHYSICS 2021; 650:L14. [PMID: 34334797 PMCID: PMC7611419 DOI: 10.1051/0004-6361/202141297] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report the detection, for the first time in space, of cyano thioformaldehyde (HCSCN) and propynethial (HCSCCH) towards the starless core TMC-1. Cyano thioformaldehyde presents a series of prominent a- and b-type lines, which are the strongest previously unassigned features in our Q-band line survey of TMC-1. Remarkably, HCSCN is four times more abundant than cyano formaldehyde (HCOCN). On the other hand, HCSCCH is five times less abundant than propynal (HCOCCH). Surprisingly, we find an abundance ratio HCSCCH/HCSCN of ∼ 0.25, in contrast with most other ethynyl-cyanide pairs of molecules for which the CCH-bearing species is more abundant than the CN-bearing one. We discuss the formation of these molecules in terms of neutral-neutral reactions of S atoms with CH2CCH and CH2CN radicals as well as of CCH and CN radicals with H2CS. The calculated abundances for the sulphur-bearing species are, however, significantly below the observed values, which points to an underestimation of the abundance of atomic sulphur in the model or to missing formation reactions, such as ion-neutral reactions.
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Affiliation(s)
- J Cernicharo
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C / Serrano 121, 28006 Madrid, Spain
| | - C Cabezas
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C / Serrano 121, 28006 Madrid, Spain
| | - Y Endo
- Department of Applied Chemistry, Science Building II, National Yang Ming Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan
| | - M Agúndez
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C / Serrano 121, 28006 Madrid, Spain
| | - B Tercero
- Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
- Observatorio Astronómico Nacional (IGN), C/Alfonso XII, 3, 28014, Madrid, Spain
| | - J R Pardo
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C / Serrano 121, 28006 Madrid, Spain
| | - N Marcelino
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C / Serrano 121, 28006 Madrid, Spain
| | - P de Vicente
- Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
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Cabezas C, Tercero B, Agúndez M, Marcelino N, Pardo JR, de Vicente P, Cernicharo J. Cumulene carbenes in TMC-1: Astronomical discovery of l-H 2C 5 ★. ASTRONOMY AND ASTROPHYSICS 2021; 650:L9. [PMID: 34334798 PMCID: PMC7611420 DOI: 10.1051/0004-6361/202141274] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report the first detection in space of the cumulene carbon chain l-H2C5. A total of eleven rotational transitions, with Jup = 7-10 and Ka = 0 and 1, were detected in TMC-1 in the 31.0-50.4 GHz range using the Yebes 40m radio telescope. We derive a column density of (1.8±0.5)×1010 cm-2. In addition, we report observations of other cumulene carbenes detected previously in TMC-1, to compare their abundances with the newly detected cumulene carbene chain. We find that l-H2C5 is ~4.0 times less abundant than the larger cumulene carbene l-H2C6, while it is ~300 and ~500 times less abundant than the shorter chains l-H2C3 and l-H2C4. We discuss the most likely gas-phase chemical routes to these cumulenes in TMC-1 and stress that chemical kinetics studies able to distinguish between different isomers are needed to shed light on the chemistry of C n H2 isomers with n > 3.
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Affiliation(s)
- C. Cabezas
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
| | - B. Tercero
- Observatorio Astronómico Nacional (IGN), C/ Alfonso XII, 3, 28014, Madrid, Spain
- Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
| | - M. Agúndez
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
| | - N. Marcelino
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
| | - J. R. Pardo
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
| | - P. de Vicente
- Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
| | - J. Cernicharo
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/ Serrano 121, 28006 Madrid, Spain
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Agúndez M, Roueff E, Cabezas C, Cernicharo J, Marcelino N. First detection of doubly deuterated methyl acetylene (CHD 2CCH and CH 2DCCD) ★. ASTRONOMY AND ASTROPHYSICS 2021; 649:A171. [PMID: 34334795 PMCID: PMC7611416 DOI: 10.1051/0004-6361/202140843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report the first detection in space of the two doubly deuterated isotopologues of methyl acetylene. The species CHD2CCH and CH2DCCD were identified in the dense core L483 through nine and eight, respectively, rotational lines in the 72-116 GHz range using the IRAM 30m telescope. The astronomical frequencies observed here were combined with laboratory frequencies from the literature measured in the 29-47 GHz range to derive more accurate spectroscopic parameters for the two isotopologues. We derive beam-averaged column densities of (2.7 ± 0.5) × 1012 cm-2 for CHD2CCH and (2.2 ± 0.4) × 1012 cm-2 for CH2DCCD, which translate to abundance ratios CH3CCH/CHD2CCH = 34 ± 10 and CH3CCH/CH2DCCD = 42 ± 13. The doubly deuterated isotopologues of methyl acetylene are only a few times less abundant than the singly deuterated ones, concretely around 2.4 times less abundant than CH3CCD. The abundances of the different deuterated isotopologues with respect to CH3CCH are reasonably accounted for by a gas-phase chemical model in which deuteration occurs from the precursor ions C3H6D+ and C3H5D+, when the ortho-to-para ratio of molecular hydrogen is sufficiently low. This points to gas-phase chemical reactions, rather than grain-surface processes, as responsible for the formation and deuterium fractionation of CH3CCH in L483. The abundance ratios CH2DCCH/CH3CCD = 3.0 ± 0.9 and CHD2CCH/CH2DCCD = 1.25 ± 0.37 observed in L483 are consistent with the statistically expected values of three and one, respectively, with the slight overabundance of CHD2CCH compared to CH2DCCD being well explained by the chemical model.
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Affiliation(s)
- M. Agúndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - E. Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, F-92190, Meudon, France
| | - C. Cabezas
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - J. Cernicharo
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - N. Marcelino
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
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6
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Agúndez M, Cabezas C, Tercero B, Marcelino N, Gallego JD, de Vicente P, Cernicharo J. Discovery of the propargyl radical (CH 2CCH) in TMC-1: one of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds. ASTRONOMY AND ASTROPHYSICS 2021; 647:L10. [PMID: 33850331 PMCID: PMC7610583 DOI: 10.1051/0004-6361/202140553] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present the first identification in interstellar space of the propargyl radical (CH2CCH). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. The six strongest hyperfine components of the 20,2-10,1 rotational transition, lying at 37.46 GHz, were detected with signal-to-noise ratios in the range 4.6-12.3 σ. We derive a column density of 8.7 × 1013 cm-2 for CH2CCH, which translates to a fractional abundance relative to H2 of 8.7 × 10-9. This radical has a similar abundance to methyl acetylene, with an abundance ratio CH2CCH/CH3CCH close to one. The propargyl radical is thus one of the most abundant radicals detected in TMC-1, and it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud. We constructed a gas-phase chemical model and find calculated abundances that agree with, or fall two orders of magnitude below, the observed value depending on the poorly constrained low-temperature reactivity of CH2CCH with neutral atoms. According to the chemical model, the propargyl radical is essentially formed by the C + C2H4 reaction and by the dissociative recombination of C3Hn + ions with n = 4-6. The propargyl radical is believed to control the synthesis of the first aromatic ring in combustion processes, and it probably plays a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds.
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Affiliation(s)
- M. Agúndez
- Instituto de Física Fundamental, CSIC, Calle Serrano 123, E-28006 Madrid, Spain
| | - C. Cabezas
- Instituto de Física Fundamental, CSIC, Calle Serrano 123, E-28006 Madrid, Spain
| | - B. Tercero
- Observatorio Astronómico Nacional, IGN, Calle Alfonso XII 3, E-28014 Madrid, Spain
- Observatorio de Yebes, IGN, Cerro de la Palera s/n, E-19141 Yebes, Guadalajara, Spain
| | - N. Marcelino
- Instituto de Física Fundamental, CSIC, Calle Serrano 123, E-28006 Madrid, Spain
| | - J. D. Gallego
- Observatorio de Yebes, IGN, Cerro de la Palera s/n, E-19141 Yebes, Guadalajara, Spain
| | - P. de Vicente
- Observatorio de Yebes, IGN, Cerro de la Palera s/n, E-19141 Yebes, Guadalajara, Spain
| | - J. Cernicharo
- Instituto de Física Fundamental, CSIC, Calle Serrano 123, E-28006 Madrid, Spain
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7
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Blázquez S, González D, Neeman EM, Ballesteros B, Agúndez M, Canosa A, Albaladejo J, Cernicharo J, Jiménez E. Gas-phase kinetics of CH 3CHO with OH radicals between 11.7 and 177.5 K. Phys Chem Chem Phys 2020; 22:20562-20572. [PMID: 32966434 PMCID: PMC7116299 DOI: 10.1039/d0cp03203d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas-phase reactions in the interstellar medium (ISM) are a source of molecules in this environment. The knowledge of the rate coefficient for neutral-neutral reactions as a function of temperature, k(T), is essential to improve astrochemical models. In this work, we have experimentally measured k(T) for the reaction between the OH radical and acetaldehyde, both present in many sources of the ISM. Laser techniques coupled to a CRESU system were used to perform the kinetic measurements. The obtained modified Arrhenius equation is k(T = 11.7-177.5 K) = (1.2 ± 0.2) × 10-11 (T/300 K)-(1.8±0.1) exp-{(28.7 ± 2.5)/T} cm3 molecule-1 s-1. The k(T) value of the title reaction has been measured for the first time below 60 K. No pressure dependence of k(T) was observed at ca. 21, 50, 64 and 106 K. Finally, a pure gas-phase model indicates that the title reaction could become the main CH3CO formation pathway in dark molecular clouds, assuming that CH3CO is the main reaction product at 10 K.
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Affiliation(s)
- Sergio Blázquez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
| | - Daniel González
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
| | - Elias M Neeman
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
| | - Bernabé Ballesteros
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain. and Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, Camino de Moledores s/n, 13071, Ciudad Real, Spain
| | - Marcelino Agúndez
- Molecular Astrophysics Group, Instituto de Física Fundamental (IFF-CSIC), Consejo Superior de Investigaciones Científicas, C/Serrano 123, 28006, Madrid, Spain
| | - André Canosa
- CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, Université de Rennes, F-35000 Rennes, France
| | - José Albaladejo
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain. and Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, Camino de Moledores s/n, 13071, Ciudad Real, Spain
| | - José Cernicharo
- Molecular Astrophysics Group, Instituto de Física Fundamental (IFF-CSIC), Consejo Superior de Investigaciones Científicas, C/Serrano 123, 28006, Madrid, Spain
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain. and Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, Camino de Moledores s/n, 13071, Ciudad Real, Spain
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8
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High-resolution rovibrational spectroscopy of c- C3H2+: The ν7 C–H antisymmetric stretching band. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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On an EUV Atmospheric Simulation Chamber to Study the Photochemical Processes of Titan's Atmosphere. Sci Rep 2020; 10:10009. [PMID: 32561886 PMCID: PMC7305212 DOI: 10.1038/s41598-020-66950-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 06/01/2020] [Indexed: 11/16/2022] Open
Abstract
The in situ exploration of Titan’s atmosphere requires the development of laboratory experiments to understand the molecular growth pathways initiated by photochemistry in the upper layers of the atmosphere. Key species and dominant reaction pathways are used to feed chemical network models that reproduce the chemical and physical processes of this complex environment. Energetic UV photons initiate highly efficient chemistry by forming reactive species in the ionospheres of the satellite. We present here a laboratory experiment based on a new closed and removable photoreactor coupled here to an Extreme Ultraviolet (EUV) irradiation beam produced by the high-order harmonic generation of a femtosecond laser. This type of EUV stable source allow long-term irradiation experiments in which a plethora of individual reactions can take place. In order to demonstrate the validity of our approach, we irradiated for 7 hours at 89.2 nm, a gas mixture based on N2/CH4 (5%). Using only one wavelength, products of the reaction reveal an efficient photochemistry with the formation of large hydrocarbons but especially organic compounds rich in nitrogen similar to Titan. Among these nitrogen compounds, new species had never before been identified in the mass spectra obtained in situ in Titan’s atmosphere. Their production in this experiment, on the opposite, corroborates previous experimental measurements in the literature on the chemical composition of aerosol analogues produced in the laboratory. Diazo-compounds such as dimethyldiazene (C2H6N2), have been observed and are consistent with the large nitrogen incorporation observed by the aerosols collector pyrolysis instrument of the Huygens probe. This work represents an important step forward in the use of a closed cell chamber irradiated by the innovative EUV source for the generation of photochemical analogues of Titan aerosols. This approach allows to better constrain and understand the growth pathways of nitrogen incorporation into organic aerosols in Titan’s atmosphere.
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Rocha CMR, Varandas AJC. A global CHIPR potential energy surface for ground-state C 3H and exploratory dynamics studies of reaction C 2 + CH → C 3 + H. Phys Chem Chem Phys 2019; 21:24406-24418. [PMID: 31663556 DOI: 10.1039/c9cp04890a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A full-dimensional global potential-energy surface (PES) is first reported for ground-state doublet C3H using the combined-hyperbolic-inverse-power-representation (CHIPR) method and accurate ab initio energies extrapolated to the complete basis set limit. The PES is based on a many-body expansion-type development where the two-body and three-body energy terms are from our previously reported analytic potentials for C2H(2A') and C3(1A',3A'), while the effective four-body one is calibrated using an extension of the CHIPR formalism for tetratomics. The final form is shown to accurately reproduce all known stationary structures of the PES, some of which are unreported thus far, and their interconversion pathways. Moreover, it warrants by built-in construction the appropriate permutational symmetry and describes in a physically reasonable manner all long-range features and the correct asymptotic behavior at dissociation. Exploratory quasi-classical trajectory calculations for the reaction C2 + CH → C3 + H are also performed, yielding thermalized rate coefficients for temperatures up to 4000 K.
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Affiliation(s)
- C M R Rocha
- Department of Chemistry and Coimbra Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.
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11
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Brünken S, Lipparini F, Stoffels A, Jusko P, Redlich B, Gauss J, Schlemmer S. Gas-Phase Vibrational Spectroscopy of the Hydrocarbon Cations l-C 3H +, HC 3H +, and c-C 3H 2+: Structures, Isomers, and the Influence of Ne-Tagging. J Phys Chem A 2019; 123:8053-8062. [PMID: 31422660 PMCID: PMC6755619 DOI: 10.1021/acs.jpca.9b06176] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
![]()
We
report the first gas-phase vibrational spectra of the hydrocarbon
ions C3H+ and C3H2+. The ions were produced by electron impact ionization of
allene. Vibrational spectra of the mass-selected ions tagged with
Ne were recorded using infrared predissociation spectroscopy in a
cryogenic ion trap instrument using the intense and widely tunable
radiation of a free electron laser. Comparison of high-level quantum
chemical calculations and resonant depletion measurements revealed
that the C3H+ ion is exclusively formed in its
most stable linear isomeric form, whereas two isomers were observed
for C3H2+. Bands of the energetically
favored cyclic c-C3H2+ are in excellent
agreement with calculated anharmonic frequencies, whereas for the
linear open-shell HCCCH+ (2Πg) a detailed theoretical description of the spectrum remains challenging
because of Renner–Teller and spin–orbit interactions.
Good agreement between theory and experiment, however, is observed
for the frequencies of the stretching modes for which an anharmonic
treatment was possible. In the case of linear l-C3H+, small but non-negligible effects of the attached Ne on the
ion fundamental band positions and the overall spectrum were found.
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Affiliation(s)
- Sandra Brünken
- FELIX Laboratory, Institute for Molecules and Materials , Radboud University , Toernooiveld 7c , NL-6525ED Nijmegen , The Netherlands.,I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
| | - Filippo Lipparini
- Institut für Physikalische Chemie , Johannes Gutenberg-Universität Mainz , Duesbergweg 10-14 , D-55128 Mainz , Germany.,Dipartimento di Chimica e Chimica Industriale , Università di Pisa , Via G. Moruzzi 13 , I-56124 Pisa , Italy
| | - Alexander Stoffels
- FELIX Laboratory, Institute for Molecules and Materials , Radboud University , Toernooiveld 7c , NL-6525ED Nijmegen , The Netherlands.,I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
| | - Pavol Jusko
- I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
| | - Britta Redlich
- FELIX Laboratory, Institute for Molecules and Materials , Radboud University , Toernooiveld 7c , NL-6525ED Nijmegen , The Netherlands
| | - Jürgen Gauss
- Institut für Physikalische Chemie , Johannes Gutenberg-Universität Mainz , Duesbergweg 10-14 , D-55128 Mainz , Germany
| | - Stephan Schlemmer
- I. Physikalisches Institut , Universität zu Köln , Zülpicher Str. 77 , D-50937 Köln , Germany
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12
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Agúndez M, Marcelino N, Cernicharo J, Roueff E, Tafalla M. A sensitive λ 3 mm line survey of L483: A broad view of the chemical composition of a core around a Class 0 object. ASTRONOMY AND ASTROPHYSICS 2019; 625:A147. [PMID: 31327870 PMCID: PMC6640051 DOI: 10.1051/0004-6361/201935164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
An exhaustive chemical characterization of dense cores is mandatory to our understanding of chemical composition changes from a starless to a protostellar stage. However, only a few sources have had their molecular composition characterized in detail. Here we present a λ 3 mm line survey of L483, a dense core around a Class 0 protostar, which was observed with the IRAM 30m telescope in the 80-116 GHz frequency range. We detected 71 molecules (140 including different isotopologs), most of which are present in the cold and quiescent ambient cloud according to their narrow lines (FWHM ~0.5 km s-1) and low rotational temperatures (≲10 K). Of particular interest among the detected molecules are the cis isomer of HCOOH, the complex organic molecules HCOOCH3, CH3OCH3, and C2H5OH, a wide variety of carbon chains, nitrogen oxides like N2O, and saturated molecules like CH3SH, in addition to eight new interstellar molecules (HCCO, HCS, HSC, NCCNH+, CNCN, NCO, H2NCO+, and NS+) whose detection has already been reported. In general, fractional molecular abundances in L483 are systematically lower than in TMC-1 (especially for carbon chains), tend to be higher than in L1544 and B1-b, and are similar to those in L1527. Apart from the overabundance of carbon chains in TMC-1, we find that L483 does not have a marked chemical differentiation with respect to starless/prestellar cores like TMC-1 and L1544, although it does chemically differentiate from Class 0 hot corino sources like IRAS 16293-2422. This fact suggests that the chemical composition of the ambient cloud of some Class 0 sources could be largely inherited from the dark cloud starless/prestellar phase. We explore the use of potential chemical evolutionary indicators, such as the HNCO/C3S, SO2/C2S, and CH3SH/C2S ratios, to trace the prestellar/protostellar transition. We also derived isotopic ratios for a variety of molecules, many of which show isotopic ratios close to the values for the local interstellar medium (remarkably all those involving 34S and 33S), while there are also several isotopic anomalies like an extreme depletion in 13C for one of the two isotopologs of c-C3H2, a drastic enrichment in 18O for SO and HNCO (SO being also largely enriched in 17O), and different abundances for the two 13C substituted species of C2H and the two 15N substituted species of N2H+. We report the first detection in space of some minor isotopologs like c-C3D. The exhaustive chemical characterization of L483 presented here, together with similar studies of other prestellar and protostellar sources, should allow us to identify the main factors that regulate the chemical composition of cores along the process of formation of low-mass protostars.
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Affiliation(s)
- M Agúndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - N Marcelino
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - J Cernicharo
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, E-28006 Madrid, Spain
| | - E Roueff
- Sorbonne Université, Observatoire de Paris, Université PSL, CNRS, LERMA, F-92190 Meudon, France
| | - M Tafalla
- Observatorio Astronómico Nacional, C/ Alfonso XII 3, E-28014 Madrid, Spain
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13
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Loison JC, Wakelam V, Gratier P, Hickson KM, Bacmann A, Agùndez M, Marcelino N, Cernicharo J, Guzman V, Gerin M, Goicoechea JR, Roueff E, Le Petit F, Pety J, Fuente A, Riviere-Marichalar P. Oxygen fractionation in dense molecular clouds. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 2019; 485:5777-5789. [PMID: 31427830 PMCID: PMC6699989 DOI: 10.1093/mnras/stz560] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have developed the first gas-grain chemical model for oxygen fractionation (also including sulphur fractionation) in dense molecular clouds, demonstrating that gas-phase chemistry generates variable oxygen fractionation levels, with a particularly strong effect for NO, SO, O2, and SO2. This large effect is due to the efficiency of the neutral 18O + NO, 18O + SO, and 18O + O2 exchange reactions. The modeling results were compared to new and existing observed isotopic ratios in a selection of cold cores. The good agreement between model and observations requires that the gas-phase abundance of neutral oxygen atoms is large in the observed regions. The S16O/S18O ratio is predicted to vary substantially over time showing that it can be used as a sensitive chemical proxy for matter evolution in dense molecular clouds.
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Affiliation(s)
- Jean-Christophe Loison
- Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - Valentine Wakelam
- Laboratoire d'astrophysique de Bordeaux, CNRS, Univ. Bordeaux, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Pierre Gratier
- Laboratoire d'astrophysique de Bordeaux, CNRS, Univ. Bordeaux, B18N, allée Geoffroy Saint-Hilaire, 33615 Pessac, France
| | - Kevin M. Hickson
- Institut des Sciences Moléculaires (ISM), CNRS, Univ. Bordeaux, 351 cours de la Libération, 33400, Talence, France
| | - Aurore Bacmann
- Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, UJF-Grenoble 1 / CNRS-INSU, 38041 Grenoble, France
| | - Marcelino Agùndez
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain
| | - Nuria Marcelino
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain
| | - José Cernicharo
- Instituto de Física Fundamental, CSIC, C/ Serrano 123, 28006 Madrid, Spain
| | - Viviana Guzman
- Joint ALMA Observatory (JAO), Alonso de Córdova 3107, Vitacura, Santiago de Chile, Chile
| | - Maryvonne Gerin
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
| | | | - Evelyne Roueff
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - Franck Le Petit
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, F-92190 Meudon, France
| | - Jérome Pety
- LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Ecole Normale Supérieure, F-75005 Paris, France
- Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint Martin d’Hyères, France
| | - Asunción Fuente
- Observatorio Astronómico Nacional (OAN, IGN), Apdo 112, E-28803 Alcalá de Henares, Spain
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14
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Ben Khalifa M, Sahnoun E, Wiesenfeld L, Khadri F, Hammami K, Dulieu O, Spezzano S, Caselli P. Rotational (de)-excitation of cyclic and linear C3H2 by collision with He. Phys Chem Chem Phys 2019; 21:1443-1453. [DOI: 10.1039/c8cp06623j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In astrochemistry, the carbenes c- and l-C3H2 are the lightest hydrocarbons to be detectable by rotational spectroscopy. We compute their interaction energy with helium atoms and the collisional quenching rates.
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Affiliation(s)
- M. Ben Khalifa
- LSMA
- Université Tunis El-Manar
- Tunis
- Tunisia
- Laboratoire Aimé-Cotton
| | - E. Sahnoun
- LSMA
- Université Tunis El-Manar
- Tunis
- Tunisia
- Laboratoire Aimé-Cotton
| | - L. Wiesenfeld
- Laboratoire Aimé-Cotton
- CNRS
- Université Paris-Saclay
- Orsay
- France
| | - F. Khadri
- LSMA
- Université Tunis El-Manar
- Tunis
- Tunisia
| | - K. Hammami
- LSMA
- Université Tunis El-Manar
- Tunis
- Tunisia
| | - O. Dulieu
- Laboratoire Aimé-Cotton
- CNRS
- Université Paris-Saclay
- Orsay
- France
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15
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Chhabra S, Dhilip Kumar TJ. Ab Initio Potential Energy Surfaces of C 3 Collision with Proton and Quantum Dynamics of Rotational Transition. J Phys Chem A 2018; 122:5437-5444. [PMID: 29791156 DOI: 10.1021/acs.jpca.8b01588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New ab initio potential energy surfaces have been generated for the ground state and low-lying excited states of the H+ + C3 system using the multireference configuration interaction (MRCI) method with Dunning's augmented correlation consistent polarized valence quadruple-zeta (aug-cc-pVQZ) basis sets. The ground state and low-lying excited states show avoided crossing, indicating nonadiabatic coupling. The anisotropy of the ground-state surface has been analyzed by computing the multipolar expansion coefficients with the frozen C-C equilibrium bond length. The asymptotic potential has been merged with the interaction potential by spline fit. This potential is then used in the full close coupling calculations of rotational excitation in C3 collision with the proton for rotational levels j = 0, 2, 4, 6, 8 at very low collision energy. By averaging the cross sections over a Boltzmann distribution of velocities of the incoming atom, we obtain and discuss corresponding rate coefficients of C3 collision with the proton in the interstellar medium.
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Affiliation(s)
- Sanchit Chhabra
- Department of Chemistry , Indian Institute of Technology Ropar , Rupnagar 140001 , India
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16
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Broderick BM, Suas-David N, Dias N, Suits AG. Isomer-specific detection in the UV photodissociation of the propargyl radical by chirped-pulse mm-wave spectroscopy in a pulsed quasi-uniform flow. Phys Chem Chem Phys 2018; 20:5517-5529. [PMID: 29165455 DOI: 10.1039/c7cp06211g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Isomer-specific detection and product branching fractions in the UV photodissociation of the propargyl radical is achieved through the use of chirped-pulse Fourier-transform mm-wave spectroscopy in a pulsed quasi-uniform flow (CPUF). Propargyl radicals are produced in the 193 nm photodissociation of 1,2-butadiene. Absorption of a second photon leads to H atom elimination giving three possible C3H2 isomers: singlets cyclopropenylidene (c-C3H2) and propadienylidene (l-C3H2), and triplet propargylene (3HCCCH). The singlet products and their appearance kinetics in the flow are directly determined by rotational spectroscopy, but due to the negligible dipole moment of propargylene, it is not directly monitored. However, we exploit the time-dependent kinetics of H-atom catalyzed isomerization to infer the branching to propargylene as well. We obtain the overall branching among H loss channels to be 2.9% (+1.1/-0.5) l-C3H2 + H, 16.8% (+3.2/-1.3) c-C3H2 + H, and 80.2 (+1.8/-4.2) 3HCCCH + H. Our findings are qualitatively consistent with earlier RRKM calculations in that the major channel in the photodissociation of the propargyl radical at 193 nm is to 3HCCCH + H; however, a greater contribution to the energetically most favorable isomer, c-C3H2 + H is observed in this work. We do not detect the predicted HCCC + H2 channel, but place an upper bound on its yield of 1%.
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Affiliation(s)
- Bernadette M Broderick
- Department of Chemistry, University of Missouri, 601 S. College Ave, Columbia MO 65211, USA.
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17
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Garcia GA, Gans B, Krüger J, Holzmeier F, Röder A, Lopes A, Fittschen C, Alcaraz C, Loison JC. Valence shell threshold photoelectron spectroscopy of C3Hx (x = 0–3). Phys Chem Chem Phys 2018. [DOI: 10.1039/c8cp00510a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present the photoelectron spectra of C3Hx (x = 0–3) formed in a microwave discharge flow-tube reactor by consecutive H abstractions from C3H4 (C3Hx + F → C3Hx−1 + HF (x = 1–4)), but also from F + CH4 schemes by secondary reactions.
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Affiliation(s)
| | | | - Julia Krüger
- Synchrotron SOLEIL
- L'Orme des Merisiers
- Gif sur Yvette
- France
| | - Fabian Holzmeier
- Synchrotron SOLEIL
- L'Orme des Merisiers
- Gif sur Yvette
- France
- Laboratoire de Chimie Physique d'Orsay
| | - Anja Röder
- Synchrotron SOLEIL
- L'Orme des Merisiers
- Gif sur Yvette
- France
| | - Allan Lopes
- CNRS – Université Paris-Sud et Paris-Saclay
- Laboratoire de Chimie Physique
- UMR 8000
- Centre Universitaire Paris-Sud
- 91405 Orsay
| | | | - Christian Alcaraz
- CNRS – Université Paris-Sud et Paris-Saclay
- Laboratoire de Chimie Physique
- UMR 8000
- Centre Universitaire Paris-Sud
- 91405 Orsay
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