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Showing 1-20 of about 75 results.
A rotational and vibrational investigation of phenylpropiolonitrile (C6H5C3N)Buchanan, ZacharyLee, Kin Long KelvinChitarra, OliviaMcCarthy, Michael C.Pirali, OlivierMartin-Drumel, Marie-AlineDOI: info:10.1016/j.jms.2021.111425v. 377111425
Buchanan, Zachary, Lee, Kin Long Kelvin, Chitarra, Olivia, McCarthy, Michael C., Pirali, Olivier, and Martin-Drumel, Marie-Aline. 2021. "A rotational and vibrational investigation of phenylpropiolonitrile (C6H5C3N)." Journal of Molecular Spectroscopy 377:111425. https://doi.org/10.1016/j.jms.2021.111425
ID: 158977
Type: article
Authors: Buchanan, Zachary; Lee, Kin Long Kelvin; Chitarra, Olivia; McCarthy, Michael C.; Pirali, Olivier; Martin-Drumel, Marie-Aline
Abstract: The evidence for benzonitrile (C6H5CN) in the starless cloud core TMC-1 makes high-resolution studies of other aromatic nitriles and their ring-chain derivatives especially timely. One such species is phenylpropiolonitrile (3-phenyl-2-propynenitrile, C6H5C3N), whose spectroscopic characterization is reported here for the first time. The low resolution (0.5 cm-1) vibrational spectrum of C6H5C3N has been recorded at far- and mid-infrared wavelengths (50-3500 cm-1) using a Fourier Transform interferometer, allowing for the assignment of band centers of 14 fundamental vibrational bands. The pure rotational spectrum of the species has been investigated using a chirped-pulse Fourier transform microwave (FTMW) spectrometer (6- 18 GHz), a cavity enhanced FTMW instrument (6-20 GHz), and a millimeter-wave one (75-100 GHz, 141-214 GHz). Through the assignment of more than 6200 lines, accurate ground state spectroscopic constants (rotational, centrifugal distortion up to octics, and nuclear quadrupole hyperfine constants) have been derived from our measurements, with a plausible prediction of the weaker lines through calculations. Interstellar searches for this highly polar species can now be undertaken with confidence since the astronomically most interesting radio lines have either been measured or can be calculated to very high accuracy below 300 GHz.
Ubiquitous aromatic carbon chemistry at the earliest stages of star formationBurkhardt, Andrew M.Loomis, Ryan A.Shingledecker, Christopher N.Lee, Kin Long KelvinRemijan, Anthony J.McCarthy, Michael C.McGuire, Brett A.DOI: info:10.1038/s41550-020-01253-4v. 5181–187
Burkhardt, Andrew M., Loomis, Ryan A., Shingledecker, Christopher N., Lee, Kin Long Kelvin, Remijan, Anthony J., McCarthy, Michael C., and McGuire, Brett A. 2021. "Ubiquitous aromatic carbon chemistry at the earliest stages of star formation." Nature Astronomy 5:181– 187. https://doi.org/10.1038/s41550-020-01253-4
ID: 159642
Type: article
Authors: Burkhardt, Andrew M.; Loomis, Ryan A.; Shingledecker, Christopher N.; Lee, Kin Long Kelvin; Remijan, Anthony J.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: Benzonitrile (c-C6H5CN, where `c' indicates a cyclic structure), a polar proxy for benzene (c-C6H6), has the potential to serve as a highly convenient radio probe for aromatic chemistry, provided that this ring can be found in other astronomical sources beyond the molecule-rich prestellar cloud TMC-1. Here we present radio astronomical evidence of benzonitrile in four other prestellar, and possibly protostellar, sources: Serpens 1A, Serpens 1B, Serpens 2 and MC27/L1521F. These detections establish that benzonitrile is not unique to TMC-1; rather, aromatic chemistry appears to be widespread throughout the earliest stages of star formation, probably persisting at least until the initial formation of a protostar. The abundance of benzonitrile far exceeds predictions from models that well reproduce the abundances of carbon chains such as HC7N, a cyanpolyyne with the same heavy atoms, indicating that the chemistry responsible for planar carbon structures (as opposed to linear ones) in primordial sources is favourable but not well understood. The abundance of benzonitrile relative to carbon chain molecules displays sizable variations between sources within the Taurus and Serpens clouds, implying the importance of physical conditions and initial elemental reservoirs of the clouds themselves.
SOLEIL and ALMA views on prototypical organic nitriles: C2H5CNEndres, Christian P.Martin-Drumel, Marie-AlineZingsheim, OliverBonah, LuisPirali, OlivierZhang, TianweiSanchez-Monge, AlvaroMoeller, ThomasWehres, NadineSchilke, PeterMcCarthy, Michael C.Schlemmer, StephanCaselli, PaolaThorwirth, SvenDOI: info:10.1016/j.jms.2020.111392v. 375111392–111392
Endres, Christian P., Martin-Drumel, Marie-Aline, Zingsheim, Oliver, Bonah, Luis, Pirali, Olivier, Zhang, Tianwei, Sanchez-Monge, Alvaro, Moeller, Thomas, Wehres, Nadine, Schilke, Peter, McCarthy, Michael C., Schlemmer, Stephan, Caselli, Paola, and Thorwirth, Sven. 2021. "SOLEIL and ALMA views on prototypical organic nitriles: C2H5CN." Journal of Molecular Spectroscopy 375:111392– 111392. https://doi.org/10.1016/j.jms.2020.111392
ID: 158181
Type: article
Authors: Endres, Christian P.; Martin-Drumel, Marie-Aline; Zingsheim, Oliver; Bonah, Luis; Pirali, Olivier; Zhang, Tianwei; Sanchez-Monge, Alvaro; Moeller, Thomas; Wehres, Nadine; Schilke, Peter; McCarthy, Michael C.; Schlemmer, Stephan; Caselli, Paola; Thorwirth, Sven
Abstract: The high resolution vibrational spectrum of ethyl cyanide (C2H5CN) has been investigated in the far-IR using synchrotron-based Fourier transform spectroscopy. The assignment was performed using the Automated Spectral Assignment Procedure (ASAP) allowing accurate rotational energy levels of the four lowest fundamental vibrations of the species, namely the v(13) = 1 @ 205.934099(8)cm(1), v(21) = 1 @ 212.141101(8)cm(1), v(20) = 1 @ 372.635293(15)cm(1), and v(12) = 1 @ 532.699617(16)cm(1) states, to be determined. The analysis not only confirms the applicability of the ASAP in the treatment of (dense) high-resolution infrared spectra but also reveals some of its limitations. Complementary to the infrared study, the pure rotational spectrum of C2H5CN was also studied in selected frequency ranges from 75 to 255 GHz. New observations of a prototypical high-mass star-forming region, G327.3-0.6, performed with the Atacama Large Millimeter Array show that vibrational satellites of C2H5CN can be very intense, of order several tens of Kelvin in units of brightness temperature. (C) 2020 Elsevier Inc. All rights reserved.
Interstellar Detection of 2-cyanocyclopentadiene, C5H5CN, a Second Five-membered Ring toward TMC-1Lee, Kin Long KelvinChangala, P. BryanLoomis, Ryan A.Burkhardt, Andrew M.Xue, CiCordiner, Martin A.Charnley, Steven B.McCarthy, Michael C.McGuire, Brett A.DOI: info:10.3847/2041-8213/abe764v. 910L2
Lee, Kin Long Kelvin, Changala, P. Bryan, Loomis, Ryan A., Burkhardt, Andrew M., Xue, Ci, Cordiner, Martin A., Charnley, Steven B., McCarthy, Michael C., and McGuire, Brett A. 2021. "Interstellar Detection of 2-cyanocyclopentadiene, C5H5CN, a Second Five-membered Ring toward TMC-1." The Astrophysical Journal 910:L2. https://doi.org/10.3847/2041-8213/abe764
ID: 159425
Type: article
Authors: Lee, Kin Long Kelvin; Changala, P. Bryan; Loomis, Ryan A.; Burkhardt, Andrew M.; Xue, Ci; Cordiner, Martin A.; Charnley, Steven B.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: Using radio observations with the Green Bank Telescope, evidence has now been found for a second five-membered ring in the dense cloud Taurus Molecular Cloud-1 (TMC-1). Based on additional observations of an ongoing, large-scale, high-sensitivity spectral line survey (GOTHAM) at centimeter wavelengths toward this source, we have used a combination of spectral stacking, Markov Chain Monte Carlo (MCMC), and matched filtering techniques to detect 2-cyanocyclopentadiene, a low-lying isomer of 1-cyanocyclopentadiene, which was recently discovered there by the same methods. The new observational data also yield a considerably improved detection significance for the more stable isomer and evidence for several individual transitions between 23-32 GHz. Through our MCMC analysis, we derive cospatial, total column densities of 8.3 × 1011 and 1.9 × 1011 cm-2 for 1- and 2-cyanocyclopentadiene, respectively, corresponding to a ratio of ∼4.4 favoring the former. The derived abundance ratios point toward a common formation pathway-most likely being cyanation of cyclopentadiene by analogy to benzonitrile.
Discovery of Interstellar trans-cyanovinylacetylene (HC ≡ CCH = CHC ≡ N) and vinylcyanoacetylene (H2C = CHC3N) in GOTHAM Observations of TMC-1Lee, Kin Long KelvinLoomis, Ryan A.Burkhardt, Andrew M.Cooke, Ilsa R.Xue, CiSiebert, Mark A.Shingledecker, Christopher N.Remijan, AnthonyCharnley, Steven B.McCarthy, Michael C.McGuire, Brett A.DOI: info:10.3847/2041-8213/abdbb9v. 908L11
Lee, Kin Long Kelvin, Loomis, Ryan A., Burkhardt, Andrew M., Cooke, Ilsa R., Xue, Ci, Siebert, Mark A., Shingledecker, Christopher N., Remijan, Anthony, Charnley, Steven B., McCarthy, Michael C., and McGuire, Brett A. 2021. "Discovery of Interstellar trans-cyanovinylacetylene (HC ≡ CCH = CHC ≡ N) and vinylcyanoacetylene (H2C = CHC3N) in GOTHAM Observations of TMC-1." The Astrophysical Journal 908:L11. https://doi.org/10.3847/2041-8213/abdbb9
ID: 159619
Type: article
Authors: Lee, Kin Long Kelvin; Loomis, Ryan A.; Burkhardt, Andrew M.; Cooke, Ilsa R.; Xue, Ci; Siebert, Mark A.; Shingledecker, Christopher N.; Remijan, Anthony; Charnley, Steven B.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: We report the discovery of two unsaturated organic species, trans-(E)-cyanovinylacetylene and vinylcyanoacetylene, using the second data release of the GOTHAM deep survey toward TMC-1 with the 100 m Green Bank Telescope. For both detections, we performed velocity stacking and matched filter analyses using Markov Chain Monte Carlo simulations, and for trans-(E)-cyanovinylacetylene, three rotational lines were observed at low signal-to-noise (∼3σ). From this analysis, we derive column densities of 2 × 1011 and 3 × 1011 cm-2 for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of for vinylcyanoacetylene and trans-(E)-cyanovinylacetylene, respectively, and an upper limit of 11 cm-2 for trans-(Z)-cyanovinylacetylene. Comparisons with G3//B3LYP semiempirical thermochemical calculations indicate abundances of the [H3C5N] isomers are not consistent with their thermodynamic stability, and instead their abundances are mainly driven by dynamics. We provide a discussion on how these species may be formed in TMC-1, with reference to related molecules like vinyl cyanide (CH2 = CHC ≡ N). As part of this discussion, we performed the same analysis for ethyl cyanide (CH3CH2C ≡ N), the hydrogenation product of CH2 = CHC ≡ N. This analysis provides evidence-at 4.2σ significance-of an upper limit to the column density of = CHC ≡ N. This analysis provides evidence-at 4.2σ significance-of an upper limit to the column density of 11 cm-2; an order of magnitude lower than previous upper limits toward this source.
An investigation of spectral line stacking techniques and application to the detection of HC11NLoomis, Ryan A.Burkhardt, Andrew M.Shingledecker, Christopher N.Charnley, Steven B.Cordiner, Martin A.Herbst, EricKalenskii, SergeiLee, Kin Long KelvinWillis, Eric R.Xue, CiRemijan, Anthony J.McCarthy, Michael C.McGuire, Brett A.DOI: info:10.1038/s41550-020-01261-4v. 5188–196
Loomis, Ryan A., Burkhardt, Andrew M., Shingledecker, Christopher N., Charnley, Steven B., Cordiner, Martin A., Herbst, Eric, Kalenskii, Sergei, Lee, Kin Long Kelvin, Willis, Eric R., Xue, Ci, Remijan, Anthony J., McCarthy, Michael C., and McGuire, Brett A. 2021. "An investigation of spectral line stacking techniques and application to the detection of HC11N." Nature Astronomy 5:188– 196. https://doi.org/10.1038/s41550-020-01261-4
ID: 159355
Type: article
Authors: Loomis, Ryan A.; Burkhardt, Andrew M.; Shingledecker, Christopher N.; Charnley, Steven B.; Cordiner, Martin A.; Herbst, Eric; Kalenskii, Sergei; Lee, Kin Long Kelvin; Willis, Eric R.; Xue, Ci; Remijan, Anthony J.; McCarthy, Michael C.; McGuire, Brett A.
Abstract: As the inventory of interstellar molecules continues to grow, the gulf between small species, whose individual rotational lines can be observed with radio telescopes, and large ones, such as polycyclic aromatic hydrocarbons best studied in bulk via infrared and optical observations, is slowly being bridged. Understanding the connection between these two molecular reservoirs is critical to understanding the interstellar carbon cycle, but will require pushing the boundaries of how far we can probe molecular complexity while still retaining observational specificity. Towards this end, we present a method for detecting and characterizing new molecular species in single-dish observations towards sources with sparse line spectra. We have applied this method to data from the ongoing GOTHAM (GBT Observations of TMC-1: Hunting Aromatic Molecules) Green Bank Telescope large programme, discovering six new interstellar species. Here we highlight the detection of HC11N, the largest cyanopolyyne in the interstellar medium.
Interstellar detection of the highly polar five-membered ring cyanocyclopentadieneMcCarthy, Michael C.Lee, Kin Long KelvinLoomis, Ryan A.Burkhardt, Andrew M.Shingledecker, Christopher N.Charnley, Steven B.Cordiner, Martin A.Herbst, EricKalenskii, SergeiWillis, Eric R.Xue, CiRemijan, Anthony J.McGuire, Brett A.DOI: info:10.1038/s41550-020-01213-yv. 5176–180
McCarthy, Michael C., Lee, Kin Long Kelvin, Loomis, Ryan A., Burkhardt, Andrew M., Shingledecker, Christopher N., Charnley, Steven B., Cordiner, Martin A., Herbst, Eric, Kalenskii, Sergei, Willis, Eric R., Xue, Ci, Remijan, Anthony J., and McGuire, Brett A. 2021. "Interstellar detection of the highly polar five-membered ring cyanocyclopentadiene." Nature Astronomy 5:176– 180. https://doi.org/10.1038/s41550-020-01213-y
ID: 159354
Type: article
Authors: McCarthy, Michael C.; Lee, Kin Long Kelvin; Loomis, Ryan A.; Burkhardt, Andrew M.; Shingledecker, Christopher N.; Charnley, Steven B.; Cordiner, Martin A.; Herbst, Eric; Kalenskii, Sergei; Willis, Eric R.; Xue, Ci; Remijan, Anthony J.; McGuire, Brett A.
Abstract: Much like six-membered rings, five-membered rings are ubiquitous in organic chemistry, frequently serving as the building blocks for larger molecules, including many of biochemical importance. From a combination of laboratory rotational spectroscopy and a sensitive spectral line survey in the radio band toward the starless cloud core TMC-1, we report the astronomical detection of 1-cyano-1,3-cyclopentadiene (1-cyano-CPD, c-C5H5CN), a highly polar, cyano derivative of cyclopentadiene. The derived abundance of 1-cyano-CPD is far greater than predicted from astrochemical models that well reproduce the abundance of many carbon chains. This finding implies that either an important production mechanism or a large reservoir of aromatic material may need to be considered. The apparent absence of its closely related isomer, 2-cyano-1,3-cyclopentadiene, may arise from that isomer's lower stability or may be indicative of a more selective pathway for formation of the 1-cyano isomer, perhaps one starting from acyclic precursors. The absence of N-heterocycles such as pyrrole and pyridine is discussed in light of the astronomical finding of 1-cyano-CPD.
Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filteringMcGuire, Brett A.Loomis, Ryan A.Burkhardt, Andrew M.Lee, Kin Long KelvinShingledecker, Christopher N.Charnley, Steven B.Cooke, Ilsa R.Cordiner, Martin A.Herbst, EricKalenskii, SergeiSiebert, Mark A.Willis, Eric R.Xue, CiRemijan, Anthony J.McCarthy, Michael C.DOI: info:10.1126/science.abb7535v. 3711265–1269
McGuire, Brett A., Loomis, Ryan A., Burkhardt, Andrew M., Lee, Kin Long Kelvin, Shingledecker, Christopher N., Charnley, Steven B., Cooke, Ilsa R., Cordiner, Martin A., Herbst, Eric, Kalenskii, Sergei, Siebert, Mark A., Willis, Eric R., Xue, Ci, Remijan, Anthony J., and McCarthy, Michael C. 2021. "Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filtering." Science 371:1265– 1269. https://doi.org/10.1126/science.abb7535
ID: 159345
Type: article
Authors: McGuire, Brett A.; Loomis, Ryan A.; Burkhardt, Andrew M.; Lee, Kin Long Kelvin; Shingledecker, Christopher N.; Charnley, Steven B.; Cooke, Ilsa R.; Cordiner, Martin A.; Herbst, Eric; Kalenskii, Sergei; Siebert, Mark A.; Willis, Eric R.; Xue, Ci; Remijan, Anthony J.; McCarthy, Michael C.
Abstract: Unidentified infrared emission bands are ubiquitous in many astronomical sources. These bands are widely, if not unanimously, attributed to collective emissions from polycyclic aromatic hydrocarbon (PAH) molecules, yet no single species of this class has been identified in space. Using spectral matched filtering of radio data from the Green Bank Telescope, we detected two nitrile-group–functionalized PAHs, 1- and 2-cyanonaphthalene, in the interstellar medium. Both bicyclic ring molecules were observed in the TMC-1 molecular cloud. In this paper, we discuss potential in situ gas-phase PAH formation pathways from smaller organic precursor molecules.
Rotational spectroscopy and bound state calculations of deuterated NH3-H2 van der Waals complexesTarabukin, I. V.Surin, L. A.Hermanns, M.Heyne, B.Schlemmer, S.Lee, K. L. K.McCarthy, Michael C.van der Avoird, A.DOI: info:10.1016/j.jms.2021.111442v. 377111442
Tarabukin, I. V., Surin, L. A., Hermanns, M., Heyne, B., Schlemmer, S., Lee, K. L. K., McCarthy, Michael C., and van der Avoird, A. 2021. "Rotational spectroscopy and bound state calculations of deuterated NH3-H2 van der Waals complexes." Journal of Molecular Spectroscopy 377:111442. https://doi.org/10.1016/j.jms.2021.111442
ID: 158975
Type: article
Authors: Tarabukin, I. V.; Surin, L. A.; Hermanns, M.; Heyne, B.; Schlemmer, S.; Lee, K. L. K.; McCarthy, Michael C.; van der Avoird, A.
Abstract: Pure rotational transitions of the deuterated NH3-H2 weakly bound complexes formed by NH3/ND3 and H2/D2, namely ND3-H2, NH3-D2 and ND3-D2, have been detected. Three different techniques, a millimeter-wave intracavity jet OROTRON spectrometer, molecular beam Fourier transform microwave (FTMW) cavity spectrometer and the broadband chirped pulse (CP) FTMW spectrometer were used to record the spectra in the frequency range from 20 to 140 GHz. The double resonance method was additionally applied to extend the frequency range of the OROTRON spectrometer to lower and of the FTMW cavity spectrometer to higher frequencies. A search for the transitions of deuterated isotopologues and their assignments were based on the recent study of the main isotopic species NH3-H2 [L.A. Surin et al., Astrophys. J., 838, 27 (2017)] and further confirmed by the bound state calculations presented here. The measured line positions including hyperfine splitting due to the 14N nuclear spin of NH3/ND3 and the D nuclear spins of D2 were analysed in order to determine the molecular parameters and structure of the deuterated NH3-H2 complexes. This study provides an effective new probe of the intermolecular interaction between ammonia and dihydrogen, knowledge of which is important for numerical modelling of astrophysical environments.
Synchrotron-Based High Resolution Far-Infrared Spectroscopy of trans-ButadieneMartin-Drumel, Marie-AlinePorterfield, Jessica P.Goubet, ManuelAsselin, PierreGeorges, RobertSoulard, PascaleNava, MatthewChangala, P. BryanBillinghurst, BrantPirali, OlivierMcCarthy, Michael C.Baraban, Joshua H.DOI: info:10.1021/acs.jpca.0c00623v. 1242427–2435
Martin-Drumel, Marie-Aline, Porterfield, Jessica P., Goubet, Manuel, Asselin, Pierre, Georges, Robert, Soulard, Pascale, Nava, Matthew, Changala, P. Bryan, Billinghurst, Brant, Pirali, Olivier, McCarthy, Michael C., and Baraban, Joshua H. 2020. "Synchrotron-Based High Resolution Far-Infrared Spectroscopy of trans-Butadiene." Journal of Physical Chemistry A 124:2427– 2435. https://doi.org/10.1021/acs.jpca.0c00623
ID: 158096
Type: article
Authors: Martin-Drumel, Marie-Aline; Porterfield, Jessica P.; Goubet, Manuel; Asselin, Pierre; Georges, Robert; Soulard, Pascale; Nava, Matthew; Changala, P. Bryan; Billinghurst, Brant; Pirali, Olivier; McCarthy, Michael C.; Baraban, Joshua H.
Molecule Identification with Rotational Spectroscopy and Probabilistic Deep LearningMcCarthy, Michael C.Lee, Kin Long KelvinDOI: info:10.1021/acs.jpca.0c01376v. 1243002–3017
McCarthy, Michael C. and Lee, Kin Long Kelvin. 2020. "Molecule Identification with Rotational Spectroscopy and Probabilistic Deep Learning." Journal of Physical Chemistry A 124:3002– 3017. https://doi.org/10.1021/acs.jpca.0c01376
ID: 158226
Type: article
Authors: McCarthy, Michael C.; Lee, Kin Long Kelvin
Abstract: A proof-of-concept framework for identifying molecules of unknown elemental composition and structure using experimental rotational data and probabilistic deep learning is presented. Using a minimal set of input data determined experimentally, we describe four neural network architectures that yield information to assist in the identification of an unknown molecule. The first architecture translates spectroscopic parameters into Coulomb matrix eigenspectra, as a method of recovering chemical and structural information encoded in the rotational spectrum. The eigenspectrum is subsequently used by three deep learning networks to constrain the range of stoichiometries, generate SMILES strings, and predict the most likely functional groups present in the molecule. In each model, we utilize dropout layers as an approximation to Bayesian sampling, which subsequently generates probabilistic predictions from otherwise deterministic models. These models are trained on a modestly sized theoretical dataset comprising ${\sim}$83,000 unique organic molecules (between 18 and 180 amu) optimized at the $\omega$B97X-D/6-31+G(d) level of theory where the theoretical uncertainty of the spectroscopic constants are well understood and used to further augment training. Since chemical and structural properties depend highly on molecular composition, we divided the dataset into four groups corresponding to pure hydrocarbons, oxygen-bearing, nitrogen-bearing, and both oxygen- and nitrogen-bearing species, training each type of network with one of these categories thus creating "experts" within each domain of molecules. We demonstrate how these models can then be used for practical inference on four molecules, and discuss both the strengths and shortcomings of our approach, and the future directions these architectures can take.
Exhaustive Product Analysis of Three Benzene Discharges by Microwave SpectroscopyMcCarthy, Michael C.Lee, Kin Long KelvinCarroll, P. BrandonPorterfield, Jessica P.Changala, P. BryanThorpe, James H.Stanton, John F.DOI: info:10.1021/acs.jpca.0c02919v. 1245170–5181
McCarthy, Michael C., Lee, Kin Long Kelvin, Carroll, P. Brandon, Porterfield, Jessica P., Changala, P. Bryan, Thorpe, James H., and Stanton, John F. 2020. "Exhaustive Product Analysis of Three Benzene Discharges by Microwave Spectroscopy." Journal of Physical Chemistry A 124:5170– 5181. https://doi.org/10.1021/acs.jpca.0c02919
Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH2CN) in TMC-1McGuire, Brett A.Burkhardt, Andrew M.Loomis, Ryan A.Shingledecker, Christopher N.Lee, Kin Long KelvinCharnley, Steven B.Cordiner, Martin A.Herbst, EricKalenskii, SergeiMomjian, EmmanuelWillis, Eric R.Xue, CiRemijan, Anthony J.McCarthy, Michael C.DOI: info:10.3847/2041-8213/aba632v. 900L10
McGuire, Brett A., Burkhardt, Andrew M., Loomis, Ryan A., Shingledecker, Christopher N., Lee, Kin Long Kelvin, Charnley, Steven B., Cordiner, Martin A., Herbst, Eric, Kalenskii, Sergei, Momjian, Emmanuel, Willis, Eric R., Xue, Ci, Remijan, Anthony J., and McCarthy, Michael C. 2020. "Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH2CN) in TMC-1." The Astrophysical Journal 900:L10. https://doi.org/10.3847/2041-8213/aba632
ID: 157685
Type: article
Authors: McGuire, Brett A.; Burkhardt, Andrew M.; Loomis, Ryan A.; Shingledecker, Christopher N.; Lee, Kin Long Kelvin; Charnley, Steven B.; Cordiner, Martin A.; Herbst, Eric; Kalenskii, Sergei; Momjian, Emmanuel; Willis, Eric R.; Xue, Ci; Remijan, Anthony J.; McCarthy, Michael C.
Abstract: We present an overview of the GBT Observations of TMC-1: Hunting Aromatic Molecules Large Program on the Green Bank Telescope. This and a related program were launched to explore the depth and breadth of aromatic chemistry in the interstellar medium at the earliest stages of star formation, following our earlier detection of benzonitrile (c-C6H5CN) in TMC-1. In this work, details of the observations, use of archival data, and data reduction strategies are provided. Using these observations, the interstellar detection of propargyl cyanide (HCCCH2CN) is described, as well as the accompanying laboratory spectroscopy. We discuss these results, and the survey project as a whole, in the context of investigating a previously unexplored reservoir of complex, gas-phase molecules in pre-stellar sources. A series of companion papers describe other new astronomical detections and analyses.
Automated Construction of Potential Energy Surfaces Suitable to Describe van der Waals Complexes with Highly Excited Nascent Molecules: The Rotational Spectra of Ar─CS(v) and Ar─SiS(v)Quintas-Sánchez, ErnestoDawes, RichardLee, KelvinMcCarthy, Michael C.DOI: info:10.1021/acs.jpca.0c02685v. 1244445–4454
Quintas-Sánchez, Ernesto, Dawes, Richard, Lee, Kelvin, and McCarthy, Michael C. 2020. "Automated Construction of Potential Energy Surfaces Suitable to Describe van der Waals Complexes with Highly Excited Nascent Molecules: The Rotational Spectra of Ar─CS(v) and Ar─SiS(v)." Journal of Physical Chemistry A 124:4445– 4454. https://doi.org/10.1021/acs.jpca.0c02685
ID: 158152
Type: article
Authors: Quintas-Sánchez, Ernesto; Dawes, Richard; Lee, Kelvin; McCarthy, Michael C.
Detecting Laser-Volatilized Salts with a Miniature 100-GHz SpectrometerRaymond, Alexander W.Lee, Kin Long KelvinMcCarthy, Michael C.Drouin, Brian J.Mazur, EricDOI: info:10.1021/acs.jpca.9b10548v. 1241429–1436
Raymond, Alexander W., Lee, Kin Long Kelvin, McCarthy, Michael C., Drouin, Brian J., and Mazur, Eric. 2020. "Detecting Laser-Volatilized Salts with a Miniature 100-GHz Spectrometer." Journal of Physical Chemistry A 124:1429– 1436. https://doi.org/10.1021/acs.jpca.9b10548
ID: 158227
Type: article
Authors: Raymond, Alexander W.; Lee, Kin Long Kelvin; McCarthy, Michael C.; Drouin, Brian J.; Mazur, Eric
Descendant of the X-ogen carrier and a 'mass of 69': infrared action spectroscopic detection of HC3O+ and HC3S+Thorwirth, SvenHarding, Michael E.Asvany, OskarBrünken, SandraJusko, PavolLee, Kin Long KelvinSalomon, ThomasMcCarthy, Michael C.Schlemmer, StephanDOI: info:10.1080/00268976.2020.1776409v. 118e1776409
Thorwirth, Sven, Harding, Michael E., Asvany, Oskar, Brünken, Sandra, Jusko, Pavol, Lee, Kin Long Kelvin, Salomon, Thomas, McCarthy, Michael C., and Schlemmer, Stephan. 2020. "Descendant of the X-ogen carrier and a 'mass of 69': infrared action spectroscopic detection of HC3O+ and HC3S+." Molecular Physics 118:e1776409. https://doi.org/10.1080/00268976.2020.1776409
ID: 158886
Type: article
Authors: Thorwirth, Sven; Harding, Michael E.; Asvany, Oskar; Brünken, Sandra; Jusko, Pavol; Lee, Kin Long Kelvin; Salomon, Thomas; McCarthy, Michael C.; Schlemmer, Stephan
Abstract: The carbon chain ions HC ? O ? and HC ? S ? - longer variants of the famous 'X-ogen' line carrier HCO ? - have been observed for the first time using two cryogenic 22-pole ion trap apparatus (FELion, Coltrap) and two different light sources: the Free Electron Laser for Infrared eXperiments (FELIX), which was operated between 460 and 2500 cm ? , and an optical parametric oscillator operating near 3200 cm ? ; signals from both experiments were detected by infrared predissociation action spectroscopy. The majority of vibrational fundamentals were observed for both ions and their wavenumbers compare very favourably with results from high-level anharmonic force field calculations performed here at the coupled-cluster singles and doubles level augmented by a perturbative treatment of triple excitations, CCSD(T). As the action scheme employed here probes the Ne-tagged weakly bound variants, Ne-HC ? O ? and Ne-HC ? S ? , corresponding calculations of these systems were also performed. Differences in the structures and molecular force fields between the bare ions and their Ne-tagged complexes are found to be very small.
Detection of Interstellar HC4NC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 ConditionsXue, CiWillis, Eric R.Loomis, Ryan A.Lee, Kin Long KelvinBurkhardt, Andrew M.Shingledecker, Christopher N.Charnley, Steven B.Cordiner, Martin A.Kalenskii, SergeiMcCarthy, Michael C.Herbst, EricRemijan, Anthony J.McGuire, Brett A.DOI: info:10.3847/2041-8213/aba631v. 900L9
Xue, Ci, Willis, Eric R., Loomis, Ryan A., Lee, Kin Long Kelvin, Burkhardt, Andrew M., Shingledecker, Christopher N., Charnley, Steven B., Cordiner, Martin A., Kalenskii, Sergei, McCarthy, Michael C., Herbst, Eric, Remijan, Anthony J., and McGuire, Brett A. 2020. "Detection of Interstellar HC4NC and an Investigation of Isocyanopolyyne Chemistry under TMC-1 Conditions." The Astrophysical Journal 900:L9. https://doi.org/10.3847/2041-8213/aba631
ID: 157670
Type: article
Authors: Xue, Ci; Willis, Eric R.; Loomis, Ryan A.; Lee, Kin Long Kelvin; Burkhardt, Andrew M.; Shingledecker, Christopher N.; Charnley, Steven B.; Cordiner, Martin A.; Kalenskii, Sergei; McCarthy, Michael C.; Herbst, Eric; Remijan, Anthony J.; McGuire, Brett A.
Abstract: We report an astronomical detection of HC4NC for the first time in the interstellar medium with the Green Bank Telescope toward the TMC-1 molecular cloud with a minimum significance of 10.5σ. The total column density and excitation temperature of HC4NC are determined to be ${3.29}_{-1.20}^{+8.60}\times {10}^{11}$ cm-2 and ${6.7}_{-0.3}^{+0.3}\ {\rm{K}}$ , respectively, using Markov chain Monte Carlo analysis. In addition to HC4NC, HCCNC is distinctly detected whereas no clear detection of HC6NC is made. We propose that the dissociative recombination of the protonated cyanopolyyne, HC5NH+, and the protonated isocyanopolyyne, HC4NCH+, are the main formation mechanisms for HC4NC while its destruction is dominated by reactions with simple ions and atomic carbon. With the proposed chemical networks, the observed abundances of HC4NC and HCCNC are reproduced satisfactorily.
Gas phase detection and rotational spectroscopy of ethynethiol, HCCSHLee, Kin Long KelvinMartin-Drumel, Marie-AlineLattanzi, ValerioMcGuire, Brett A.Caselli, PaolaMcCarthy, Michael C.DOI: info:10.1080/00268976.2018.1552028v. 1171381–1391
Lee, Kin Long Kelvin, Martin-Drumel, Marie-Aline, Lattanzi, Valerio, McGuire, Brett A., Caselli, Paola, and McCarthy, Michael C. 2019. "Gas phase detection and rotational spectroscopy of ethynethiol, HCCSH." Molecular Physics 117:1381– 1391. https://doi.org/10.1080/00268976.2018.1552028
ID: 152909
Type: article
Authors: Lee, Kin Long Kelvin; Martin-Drumel, Marie-Aline; Lattanzi, Valerio; McGuire, Brett A.; Caselli, Paola; McCarthy, Michael C.
Abstract: We report the gas-phase detection and spectroscopic characterisation of ethynethiol (?), a metastable isomer of thioketene (?) using a combination of Fourier-transform microwave and submillimetre-wave spectroscopies. Several a-type transitions of the normal species were initially detected below 40 GHz using a supersonic expansion-electrical discharge source, and subsequent measurement of higher-frequency, b-type lines using double resonance provided accurate predictions in the submillimetre region. With these, searches using a millimetre-wave absorption spectrometer equipped with a radio frequency discharge source were conducted in the range 280-660 GHz, ultimately yielding nearly 100 transitions up to ? and ?. From the combined data set, all three rotational constants and centrifugal distortion terms up to the sextic order were determined to high accuracy, providing a reliable set of frequency predictions to the lower end of the THz band. Isotopic substitution has enabled both a determination of the molecular structure of HCCSH and, by inference, its formation pathway in our nozzle discharge source via the bimolecular radical-radical recombination reaction ?, which is calculated to be highly exothermic (-477 kJ/mol) using the HEAT345(Q) thermochemical scheme.
Gas-phase synthetic pathways to benzene and benzonitrile: a combined microwave and thermochemical investigationLee, Kin Long KelvinMcGuire, Brett A.McCarthy, Michael C.DOI: info:10.1039/C8CP06070Cv. 212946–2956
Lee, Kin Long Kelvin, McGuire, Brett A., and McCarthy, Michael C. 2019. "Gas-phase synthetic pathways to benzene and benzonitrile: a combined microwave and thermochemical investigation." Physical Chemistry Chemical Physics (Incorporating Faraday Transactions) 21:2946– 2956. https://doi.org/10.1039/C8CP06070C
ID: 150505
Type: article
Authors: Lee, Kin Long Kelvin; McGuire, Brett A.; McCarthy, Michael C.
Abstract: Not Available
Submillimeter spectroscopy and astronomical searches of vinyl mercaptan, C2H3SHMartin-Drumel, Marei-AlineLee, K. L. K.Belloche, A.Zingsheim, O.Thorwirth, S.Müller, H. S. P.Lewen, F.Garrod, R. T.Menten, K. M.McCarthy, Michael C.Schlemmer, S.DOI: info:10.1051/0004-6361/201935032v. 623A167
Martin-Drumel, Marei-Aline, Lee, K. L. K., Belloche, A., Zingsheim, O., Thorwirth, S., Müller, H. S. P., Lewen, F., Garrod, R. T., Menten, K. M., McCarthy, Michael C., and Schlemmer, S. 2019. "Submillimeter spectroscopy and astronomical searches of vinyl mercaptan, C2H3SH." Astronomy and Astrophysics 623:A167. https://doi.org/10.1051/0004-6361/201935032
ID: 155404
Type: article
Authors: Martin-Drumel, Marei-Aline; Lee, K. L. K.; Belloche, A.; Zingsheim, O.; Thorwirth, S.; Müller, H. S. P.; Lewen, F.; Garrod, R. T.; Menten, K. M.; McCarthy, Michael C.; Schlemmer, S.
Abstract: Context. New laboratory investigations of the rotational spectrum of postulated astronomical species are essential to support the assignment and analysis of current astronomical surveys. In particular, considerable interest surrounds sulfur analogs of oxygen-containing interstellar molecules and their isomers. Aims: To enable reliable interstellar searches of vinyl mercaptan, the sulfur-containing analog to the astronomical species vinyl alcohol, we investigated its pure rotational spectrum at millimeter wavelengths. Methods: We extended the pure rotational investigation of the two isomers syn and anti vinyl mercaptan to the millimeter domain using a frequency- multiplication spectrometer. The species were produced by a radiofrequency discharge in 1,2-ethanedithiol. Additional transitions were remeasured in the centimeter band using Fourier-transform microwave spectroscopy to better determine rest frequencies of transitions with low-J and low-Ka values. Experimental investigations were supported by quantum chemical calculations on the energetics of both the [C2,H4,S] and [C2,H4,O] isomeric families. Interstellar searches for both syn and anti vinyl mercaptan as well as vinyl alcohol were performed in the EMoCA spectral line survey carried out toward Sgr B2(N2) with ALMA. Results: Highly accurate experimental frequencies (to better than 100 kHz accuracy) for both syn and anti isomers of vinyl mercaptan are measured up to 250 GHz; these deviate considerably from predictions based on extrapolation of previous microwave measurements. Reliable frequency predictions of the astronomically most interesting millimeter-wave lines for these two species can now be derived from the best-fit spectroscopic constants. From the energetic investigations, the four lowest singlet isomers of the [C2,H4,S] family are calculated to be nearly isoenergetic, which makes this family a fairly unique test bed for assessing possible reaction pathways. Upper limits for the column density of syn and anti vinyl mercaptan are derived toward the extremely molecule-rich star-forming region Sgr B2(N2) enabling comparison with selected complex organic molecules. Tables B.1 and B.2 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz- bin/qcat?J/A+A/623/A167