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Crabtree KN, Westerfield JH, Dim CA, Meyer KS, Johansen SL, Buchanan ZS, Stucky PA. Rotational spectroscopy of methyl tert-butyl ether with a new Ka band chirped-pulse Fourier transform microwave spectrometer. Phys Chem Chem Phys 2024; 26:13694-13709. [PMID: 38666410 DOI: 10.1039/d4cp00797b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2024]
Abstract
Chirped-pulse Fourier transform microwave (CP-FTMW) spectroscopy is a powerful tool for performing broadband gas-phase rotational spectroscopy, and its applications include discovery of new molecules, complex mixture analysis, and exploration of fundamental molecular physics. Here we report the development of a new Ka band (26.5-40 GHz) CP-FTMW spectrometer that is equipped with a pulsed supersonic expansion source and a heated reservoir for low-volatility samples. The spectrometer is built around a 150 W traveling wave tube amplifier and has an instantaneous bandwidth that covers the entire Ka band spectral range. To test the performance of the spectrometer, the rotational spectrum of methyl tert-butyl ether (MTBE), a former gasoline additive and environmental pollutant, has been measured for the first time in this spectral range. Over 1000 spectroscopic transitions have been measured and assigned to the vibrational ground state and a newly-identified torsionally excited state; all transitions were fit using the XIAM program to a root-mean-square deviation of 22 kHz. The spectrum displays internal rotation splitting, nominally forbidden transitions, and an intriguing axis-switching effect between the ground and torsionally excited state that is a consequence of MTBE's extreme near-prolate nature. Finally, the sensitivity of the spectrometer enabled detection of all singly-substituted 13C and 18O isotopologues in natural abundance. This set of isotopic spectra allowed for a partial r0 structure involving the heavy atoms to be derived, resolving a structural discrepancy in the literature between previous microwave and electron diffraction measurements.
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Affiliation(s)
- Kyle N Crabtree
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - J H Westerfield
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Chisom A Dim
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Kelly S Meyer
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Sommer L Johansen
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Zachary S Buchanan
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
| | - Paul A Stucky
- Department of Chemistry, University of California, Davis, Davis, CA, USA.
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Meyer KS, Westerfield JH, Johansen SL, Keane J, Wannenmacher AC, Crabtree KN. Correction to "Rotational and Vibrational Spectra of the Pyridyl Radicals: A Coupled-Cluster Study". J Phys Chem A 2022; 126:4562. [PMID: 35771207 DOI: 10.1021/acs.jpca.2c04094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Xu Z, Federman S, Jackson WM, Ng CY, Wang LP, Crabtree KN. Multireference configuration interaction study of the predissociation of C 2 via its F 1Π u state. J Chem Phys 2022; 157:024302. [DOI: 10.1063/5.0097451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Photodissociation is one of the main destruction pathways for dicarbon (C2) in astronomical environments such as diffuse interstellar clouds, yet the accuracy of modern astrochemical models is limited by a lack of accurate photodissociation cross sections in the vacuum ultraviolet range. C2 features a strong predissociative F 1Πu-X 1Σg+ electronic transition near 130 nm originally measured in 1969; however, no experimental studies of this transition have been carried out since, and theoretical studies of the F 1Πu state are limited. In this work, potential energy curves of excited electronic states of C2 are calculated with the aim of describing the predissociative nature of the F 1Πu state and providing new ab initio photodissociation cross sections for astrochemical applications. Accurate electronic calculations of 56 singlet, triplet, and quintet states are carried out at the DW-SA-CASSCF/MRCI+Q level of theory with a CAS(8,12) active space and the aug-cc-pV5Z basis set augmented with additional diffuse functions. Photodissociation cross sections arising from the vibronic ground state to the F 1Πu state are calculated by a coupled-channel model. The total integrated cross section through the F 1Πu v=0 and v=1 bands is 1.198×10−13 cm2cm-1, giving rise to a photodissociation rate of 5.02×10−10 s−1 under the standard interstellar radiation field, much larger than the rate in the Leiden photodissociation database. In addition, we report a new 2 1Σu+ state that should be detectable via a strong 2 1Σu+-X 1Σg+ band around 116 nm.
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Affiliation(s)
- Zhongxing Xu
- Chemistry, University of California Davis Department of Chemistry, United States of America
| | - Steven Federman
- Deparment of Physics and Astronomy, The University of Toledo, United States of America
| | - William M. Jackson
- Department of Chemistry, University of California Davis Department of Chemistry, United States of America
| | - Cheuk-Yiu Ng
- Department of Chemistry, University of California, Davis, United States of America
| | | | - Kyle N Crabtree
- Chemistry, University of California Davis Department of Chemistry, United States of America
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4
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Meyer KS, Westerfield JH, Johansen SL, Keane J, Wannenmacher AC, Crabtree KN. Rotational and Vibrational Spectra of the Pyridyl Radicals: A Coupled-Cluster Study. J Phys Chem A 2022; 126:3185-3197. [PMID: 35549287 DOI: 10.1021/acs.jpca.2c01761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyridyl is a prototypical nitrogen-containing aromatic radical that may be a key intermediate in the formation of nitrogen-containing aromatic molecules under astrophysical conditions. On meteorites, a variety of complex molecules with nitrogen-containing rings have been detected with nonterrestrial isotopic abundances, and larger nitrogen-containing polycyclic aromatic hydrocarbons (PANHs) have been proposed to be responsible for certain unidentified infrared emission bands in the interstellar medium. In this work, the three isomers of pyridyl (2-, 3-, and 4-pyridyl) have been investigated with coupled cluster methods. For each species, structures were optimized at the CCSD(T)/cc-pwCVTZ level of theory and force fields were calculated at the CCSD(T)/ANO0 level of theory. Second-order vibrational perturbation theory (VPT2) was used to derive anharmonic vibrational frequencies and vibrationally corrected rotational constants, and resonances among vibrational states below 3500 cm-1 were treated variationally with the VPT2+K method. The results yield a complete set of spectroscopic parameters needed to simulate the pure rotational spectrum of each isomer, including electron-spin, spin-spin, and nuclear hyperfine interactions, and the calculated hyperfine parameters agree well with the limited available data from electron paramagnetic resonance spectroscopy. For the handful of experimentally measured vibrational frequencies determined from photoelectron spectroscopy and matrix isolation spectroscopy, the typical agreement is comparable to experimental uncertainty. The predicted parameters for rotational spectroscopy reported here can guide new experimental investigations into the yet-unobserved rotational spectra of these radicals.
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Affiliation(s)
- Kelly S Meyer
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - John H Westerfield
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Sommer L Johansen
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Jasmine Keane
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Anna C Wannenmacher
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Kyle N Crabtree
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
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Johansen SL, Xu Z, Westerfield JH, Wannenmacher AC, Crabtree KN. Coupled Cluster Characterization of 1-, 2-, and 3-Pyrrolyl: Parameters for Vibrational and Rotational Spectroscopy. J Phys Chem A 2021; 125:1257-1268. [PMID: 33502858 DOI: 10.1021/acs.jpca.0c09833] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyrrolyl (C4H4N) is a nitrogen-containing aromatic radical that is a derivative of pyrrole (C4H5N) and is an important intermediate in the combustion of biomass. It is also relevant for chemistry in Titan's atmosphere and may be present in the interstellar medium. The lowest-energy isomer, 1-pyrrolyl, has been involved in many experimental and theoretical studies of the N-H photodissociation of pyrrole, yet it has only been directly spectroscopically detected via electron paramagnetic resonance and through the photoelectron spectrum of the pyrrolide anion, yielding three vibrational frequencies. No direct measurements of 2- or 3-pyrrolyl have been made, and little information is known from theoretical calculations beyond their relative energies. Here, we present an ab initio quantum chemical characterization of the three pyrrolyl isomers at the CCSD(T) level of theory in their ground electronic states, with an emphasis on spectroscopic parameters relevant for vibrational and rotational spectroscopy. Equilibrium geometries were optimized at the CCSD(T)/cc-pwCVTZ level of theory, and the quadratic, cubic, and partial quartic force constants were evaluated at CCSD(T)/ANO0 for analysis using second-order vibrational perturbation theory to obtain harmonic and anharmonic vibrational frequencies. In addition, zero-point-corrected rotational constants, electronic spin-rotation tensors, and nuclear hyperfine tensors are calculated for rotational spectroscopy. Our computed structures and energies agree well with earlier density functional theory calculations, and spectroscopic parameters for 1-pyrrolyl are compared with the limited existing experimental data. Finally, we discuss strategies for detecting these radicals using rotational and vibrational spectroscopy on the basis of the calculated spectroscopic constants.
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Affiliation(s)
- Sommer L Johansen
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Zhongxing Xu
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - J H Westerfield
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Anna C Wannenmacher
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Kyle N Crabtree
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
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Johansen SL, Martin-Drumel MA, Crabtree KN. Rotational Spectrum of the β-Cyanovinyl Radical: A Possible Astrophysical N-Heterocycle Precursor. J Phys Chem A 2019; 123:5171-5177. [PMID: 31135161 DOI: 10.1021/acs.jpca.9b03798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fundamental question in the field of astrochemistry is whether the molecules essential to life originated in the interstellar medium (ISM), and, if so, how they were formed. Nitrogen-containing heterocycles are of particular interest because of their role in biology; however, to date, no N-heterocycle has been detected in the ISM, and it is unclear how and where such species might form. Recently, the β-cyanovinyl radical (HCCHCN) was implicated in the low-temperature gas-phase formation of pyridine. While neutral vinyl cyanide (H2CCHCN) has been rotationally characterized and detected in the ISM, HCCHCN has not. Here, we present the first theoretical study of all three cyanovinyl isomers at the CCSD(T)/ANO1 level of theory and the experimental rotational spectra of cis- and trans-HCCHCN, as well as those of their 15N isotopologues, from 5 to 75 GHz. The observed spectra are in good agreement with calculations and provide a basis for further laboratory and astronomical investigations of these radicals.
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Affiliation(s)
- Sommer L Johansen
- Department of Chemistry , University of California , Davis, One Shields Ave., Davis , California 95616 , United States
| | - Marie-Aline Martin-Drumel
- Institut des Sciences Moléculaires d'Orsay , CNRS, Univ. Paris-Sud, Université Paris-Saclay , F-91405 Orsay , France
| | - Kyle N Crabtree
- Department of Chemistry , University of California , Davis, One Shields Ave., Davis , California 95616 , United States
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Affiliation(s)
| | | | | | - Caroline C. Womack
- Department
of Chemistry, MIT, Cambridge, Massachusetts 02138, United States
| | - John F. Stanton
- Department of Chemistry & Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, United States
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8
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Nava M, Martin-Drumel MA, Lopez CA, Crabtree KN, Womack CC, Nguyen TL, Thorwirth S, Cummins CC, Stanton JF, McCarthy MC. Spontaneous and Selective Formation of HSNO, a Crucial Intermediate Linking H2S and Nitroso Chemistries. J Am Chem Soc 2016; 138:11441-4. [DOI: 10.1021/jacs.6b05886] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Matthew Nava
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Marie-Aline Martin-Drumel
- Harvard-Smithsonian
Center for Astrophysics and School of Engineering
and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Christopher A. Lopez
- Institute
for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Kyle N. Crabtree
- Harvard-Smithsonian
Center for Astrophysics and School of Engineering
and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Caroline C. Womack
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Thanh L. Nguyen
- Institute
for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Sven Thorwirth
- I. Physikalisches
Institut, Universität zu Köln, 50937 Köln, Germany
| | - Christopher C. Cummins
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - John F. Stanton
- Institute
for Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Michael C. McCarthy
- Harvard-Smithsonian
Center for Astrophysics and School of Engineering
and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
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9
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Crabtree KN, Martin-Drumel MA, Brown GG, Gaster SA, Hall TM, McCarthy MC. Microwave spectral taxonomy: A semi-automated combination of chirped-pulse and cavity Fourier-transform microwave spectroscopy. J Chem Phys 2016; 144:124201. [PMID: 27036440 DOI: 10.1063/1.4944072] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Because of its structural specificity, rotational spectroscopy has great potential as an analytical tool for characterizing the chemical composition of complex gas mixtures. However, disentangling the individual molecular constituents of a rotational spectrum, especially if many of the lines are entirely new or unknown, remains challenging. In this paper, we describe an empirical approach that combines the complementary strengths of two techniques, broadband chirped-pulse Fourier transform microwave spectroscopy and narrowband cavity Fourier transform microwave spectroscopy, to characterize and assign lines. This procedure, called microwave spectral taxonomy, involves acquiring a broadband rotational spectrum of a rich mixture, categorizing individual lines based on their relative intensities under series of assays, and finally, linking rotational transitions of individual chemical compounds within each category using double resonance techniques. The power of this procedure is demonstrated for two test cases: a stable molecule with a rich spectrum, 3,4-difluorobenzaldehyde, and products formed in an electrical discharge through a dilute mixture of C2H2 and CS2, in which spectral taxonomy has enabled the identification of propynethial, HC(S)CCH.
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Affiliation(s)
- Kyle N Crabtree
- Department of Chemistry, University of California, Davis, Davis, California 95616, USA
| | - Marie-Aline Martin-Drumel
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | | | | | - Taylor M Hall
- Coker College, Hartsville, South Carolina 29550, USA
| | - Michael C McCarthy
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
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McCarthy MC, Martinez O, McGuire BA, Crabtree KN, Martin-Drumel MA, Stanton JF. Isotopic studies of trans- and cis-HOCO using rotational spectroscopy: Formation, chemical bonding, and molecular structures. J Chem Phys 2016; 144:124304. [DOI: 10.1063/1.4944070] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Michael C. McCarthy
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - Oscar Martinez
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - Brett A. McGuire
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
- National Radio Astronomy Observatory, Charlottesville, Virginia 22901, USA
| | - Kyle N. Crabtree
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - Marie-Aline Martin-Drumel
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - John F. Stanton
- Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA
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Martin-Drumel MA, McCarthy MC, Patterson D, McGuire BA, Crabtree KN. Automated microwave double resonance spectroscopy: A tool to identify and characterize chemical compounds. J Chem Phys 2016; 144:124202. [DOI: 10.1063/1.4944089] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Marie-Aline Martin-Drumel
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - Michael C. McCarthy
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
- School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA
| | - David Patterson
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Brett A. McGuire
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
- National Radio Astronomy Observatory, Charlottesville, Virginia 22903, USA
| | - Kyle N. Crabtree
- Department of Chemistry, University of California, Davis, Davis, California 95616, USA
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Thorwirth S, Kaiser RI, Crabtree KN, McCarthy MC. Spectroscopic and structural characterization of three silaisocyanides: exploring an elusive class of reactive molecules at high resolution. Chem Commun (Camb) 2015; 51:11305-8. [PMID: 26083592 DOI: 10.1039/c5cc02548f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Silaisocyanoacetylene, HCCNSi, silaisocyanodiacetylene, HC4NSi, and silaisocyanogen, NCNSi, have been identified spectroscopically for the first time. All three transient species were observed at high spectral resolution at centimeter wavelengths (5-40 GHz) by microwave spectroscopy. From detection of less abundant isotopic species and high-level quantum-chemical calculations, accurate empirical equilibrium structures have been derived for HCCNSi and NCNSi. All three molecules are promising candidates for future radio astronomical detection owing in part to large calculated dipole moments.
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Affiliation(s)
- Sven Thorwirth
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany.
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Martinez O, Crabtree KN, Gottlieb CA, Stanton JF, McCarthy MC. An Accurate Molecular Structure of Phenyl, the Simplest Aryl Radical. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201409896] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Martinez O, Crabtree KN, Gottlieb CA, Stanton JF, McCarthy MC. An Accurate Molecular Structure of Phenyl, the Simplest Aryl Radical. Angew Chem Int Ed Engl 2014; 54:1808-11. [DOI: 10.1002/anie.201409896] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Indexed: 11/11/2022]
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Womack CC, Crabtree KN, McCaslin L, Martinez O, Field RW, Stanton JF, McCarthy MC. Gas-Phase Structure Determination of Dihydroxycarbene, One of the Smallest Stable Singlet Carbenes. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201311082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Womack CC, Crabtree KN, McCaslin L, Martinez O, Field RW, Stanton JF, McCarthy MC. Gas-Phase Structure Determination of Dihydroxycarbene, One of the Smallest Stable Singlet Carbenes. Angew Chem Int Ed Engl 2014; 53:4089-92. [DOI: 10.1002/anie.201311082] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 01/27/2014] [Indexed: 11/10/2022]
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Crabtree KN, Talipov MR, Martinez O, O'Connor GD, Khursan SL, McCarthy MC. Detection and structure of HOON: microwave spectroscopy reveals an O-O bond exceeding 1.9 Å. Science 2013; 342:1354-7. [PMID: 24337293 DOI: 10.1126/science.1244180] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Nitric oxide (NO) reacts with hydroxyl radicals (OH) in the gas phase to produce nitrous acid, HONO, but essentially nothing is known about the isomeric nitrosyl-O-hydroxide (HOON), owing to its perceived instability. We report the detection of gas-phase HOON in a supersonic molecular beam by Fourier transform microwave spectroscopy and a precise determination of its molecular structure by further spectroscopic analysis of its (2)H, (15)N, and (18)O isotopologs. HOON contains the longest O-O bond in any known molecule (1.9149 ± 0.0005 Å) and appears surprisingly stable, with an abundance roughly 3% that of HONO in our experiments.
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Affiliation(s)
- Kyle N Crabtree
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
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18
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Affiliation(s)
- Kyle N. Crabtree
- Harvard−Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Oscar Martinez
- Harvard−Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Michael C. McCarthy
- Harvard−Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, United States
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McCarthy MC, Martinez O, Crabtree KN, Lattanzi V, Novick SE, Thorwirth S. Detection of Nitrogen-Protonated Nitrous Oxide (HNNO+) by Rotational Spectroscopy. J Phys Chem A 2013; 117:9968-74. [DOI: 10.1021/jp4002065] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael C. McCarthy
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge,
Massachusetts 02138, United States
| | - Oscar Martinez
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge,
Massachusetts 02138, United States
| | - Kyle N. Crabtree
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge,
Massachusetts 02138, United States
| | - Valerio Lattanzi
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge,
Massachusetts 02138, United States
| | - Stewart E. Novick
- Department of Chemistry, Wesleyan University, Middletown, Connecticut 06459,
United States
| | - Sven Thorwirth
- I. Physikalisches
Institut, Universität zu Köln, Zülpicher
Strasse 77, 50937 Köln, Germany
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20
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Affiliation(s)
- Kyle N. Crabtree
- Harvard−Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts
02138, United States
| | - Benjamin J. McCall
- Departments
of Chemistry, Astronomy, and Physics, University of Illinois, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
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Abstract
Sulfoxylic acid (HOSOH), a chemical intermediate roughly midway along the path between highly reduced (H2S) and highly oxidized sulfur (H2SO4), has been detected using Fourier transform microwave spectroscopy and double resonance techniques, guided by new high-level CCSD(T) quantum-chemical calculations of its molecular structure. Rotational spectra of the two most stable isomers of HOSOH, the putative ground state with C2 symmetry and the low-lying C(s) rotamer, have been measured to high precision up to 71 GHz, allowing accurate spectroscopic parameters to be derived for both isomers. HOSOH may play a role in atmospheric and interstellar chemistry, and the present work provides the essential data to enable remote sensing and/or radioastronomical searches for these species. Spectroscopic characterization of HOSOH suggests that other transient intermediates in the oxidation of SO2 to H2SO4 may be amenable to laboratory detection as well.
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Affiliation(s)
- Kyle N Crabtree
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138, USA
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Abstract
In diffuse molecular clouds, the nuclear spin temperature of H(3)(+) (approx. 30 K) is much lower than the cloud kinetic temperature (approx. 70 K). To understand this temperature discrepancy, we have measured the ratio of the hop to exchange pathways (α) in the H(3)(+) + H(2) --> H(2) + H(3)(+) reaction (which interconverts ortho- and para-H(3)(+)) using high-resolution spectroscopy of the ν(2) fundamental band of H(3)(+) in a hydrogenic plasma. We find that α decreases from 1.6±0.1 at 350 K to its statistical value of 0.5±0.1 at 135 K. We use this result to model the steady-state chemistry of diffuse molecular clouds, finding good agreement with astronomical data provided the dissociative recombination rates of ortho- and para-H(3)(+) are equal and the identity branching fraction for the H(3)(+) + H(2) reaction is large. Our results highlight the need for further studies of the H(3)(+) + H(2) reaction as well as state-selective measurements of H(3)(+) dissociative recombination.
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Affiliation(s)
- Kyle N Crabtree
- Department of Chemistry, University of Illinois, Urbana, IL 61801, USA
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Crabtree KN, Hodges JN, Siller BM, Perry AJ, Kelly JE, Jenkins PA, McCall BJ. Sub-Doppler mid-infrared spectroscopy of molecular ions. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.09.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Crabtree KN, Kauffman CA, Tom BA, Beçka E, McGuire BA, McCall BJ. Nuclear spin dependence of the reaction of H3+ with H2. II. Experimental measurements. J Chem Phys 2011; 134:194311. [DOI: 10.1063/1.3587246] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Crabtree KN, Tom BA, McCall BJ. Nuclear spin dependence of the reaction of H3+ with H2. I. Kinetics and modeling. J Chem Phys 2011; 134:194310. [DOI: 10.1063/1.3587245] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Crabtree KN, Kauffman CA, McCall BJ. Note: A modular and robust continuous supersonic expansion discharge source. Rev Sci Instrum 2010; 81:086103. [PMID: 20815632 DOI: 10.1063/1.3478019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A direct current discharge has been coupled with a continuous supersonic expansion to provide a source of rotationally cold molecular ions for gas phase spectroscopy. Constructed primarily of machinable ceramic and stainless steel, this source design is modular, customizable, and robust. Its performance has been assessed by recording transitions within the nu(2) fundamental band of H(3) (+) using cavity ringdown spectroscopy to determine the rotational temperature of ions produced in the free-jet expansion. Temperature and column density were recorded as a function of discharge current as the source was operated over a period of 200 h. Observed temperatures ranged between 50-110 K, and the ion column densities between 8x10(10) and 2x10(12) cm(-2).
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Affiliation(s)
- Kyle N Crabtree
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, USA
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Tom BA, Mills AA, Wiczer MB, Crabtree KN, McCall BJ. Communications: Development and characterization of a source of rotationally cold, enriched para-H3+. J Chem Phys 2010; 132:081103. [DOI: 10.1063/1.3322827] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Tom BA, Zhaunerchyk V, Wiczer MB, Mills AA, Crabtree KN, Kaminska M, Geppert WD, Hamberg M, af Ugglas M, Vigren E, van der Zande WJ, Larsson M, Thomas RD, McCall BJ. Dissociative recombination of highly enriched para-H3+. J Chem Phys 2009; 130:031101. [DOI: 10.1063/1.3065970] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Crabtree KN, Hostetler KJ, Munsch TE, Neuhaus P, Lahti PM, Sander W, Poole JS. Comparative study of the photochemistry of the azidopyridine 1-oxides. J Org Chem 2008; 73:3441-51. [PMID: 18399657 DOI: 10.1021/jo8001936] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The photochemistry of azidopyridine 1-oxides was studied using an array of glass and matrix isolation techniques. As with room temperature, the photochemistry of 4-azidopyridine 1-oxide is dominated by triplet nitrene chemistry. However, in the case of the 3-azide, matrix photolysis indicates the formation of diazabicyclo[4.1.0]hepta-2,4,6-triene N-oxide and diazacycloheptatetraene N-oxide intermediates as well as triplet nitrene.
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Affiliation(s)
- Kyle N Crabtree
- Department of Chemistry, Ball State University, Muncie, Indiana 47306, USA
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Abstract
Laser flash photolysis of 4-azidopyridine-1-oxide at 266 or 308 nm yields triplet 4-nitrenopyridine-1-oxide as the dominant reactive intermediate species, with k(ISC) of approximately 2 x 10(7) s(-1). No evidence of products arising from the singlet nitrene was observed, indicating a slow rate of cyclization to the benzazirine and didehydroazepine species. The slow rate of cyclization is postulated to be due to the aminoxyl-like electronic configuration of this species, which withdraws spin density from sites for potential cyclization.
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