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Das A, Mandal PK, Lovas FJ, Medcraft C, Walker NR, Arunan E. The H
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S Dimer is Hydrogen‐Bonded: Direct Confirmation from Microwave Spectroscopy. Angew Chem Int Ed Engl 2018; 57:15199-15203. [DOI: 10.1002/anie.201808162] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Arijit Das
- Inorganic and Physical Chemistry DepartmentIndian Institute of Science Bangalore 560012 India
| | - Pankaj K. Mandal
- Indian Institute of Science Education and Research, Pune Dr. HomiBhabha Road Pune 411008 India
| | - Frank J. Lovas
- Sensor Science DivisionNational Institute of Standards and Technology 100 Bureau Dr. Gaithersburg MD 20899-8441 USA
| | - Chris Medcraft
- Department of Physics and Astronomy, LaserLaBVU University de Boelelaan 1081 1081 HV Amsterdam The Netherlands
| | - Nicholas R. Walker
- Chemistry- School of Natural and Environmental SciencesNewcastle University Bedson Building Newcastle-upon-Tyne NE1 7RU UK
| | - Elangannan Arunan
- Inorganic and Physical Chemistry DepartmentIndian Institute of Science Bangalore 560012 India
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Das A, Mandal PK, Lovas FJ, Medcraft C, Walker NR, Arunan E. The H
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S Dimer is Hydrogen‐Bonded: Direct Confirmation from Microwave Spectroscopy. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201808162] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Arijit Das
- Inorganic and Physical Chemistry DepartmentIndian Institute of Science Bangalore 560012 India
| | - Pankaj K. Mandal
- Indian Institute of Science Education and Research, Pune Dr. HomiBhabha Road Pune 411008 India
| | - Frank J. Lovas
- Sensor Science DivisionNational Institute of Standards and Technology 100 Bureau Dr. Gaithersburg MD 20899-8441 USA
| | - Chris Medcraft
- Department of Physics and Astronomy, LaserLaBVU University de Boelelaan 1081 1081 HV Amsterdam The Netherlands
| | - Nicholas R. Walker
- Chemistry- School of Natural and Environmental SciencesNewcastle University Bedson Building Newcastle-upon-Tyne NE1 7RU UK
| | - Elangannan Arunan
- Inorganic and Physical Chemistry DepartmentIndian Institute of Science Bangalore 560012 India
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Ilyushin VV, Johnson AM, Hohl J, Cloessner EA, Lovas FJ, Lavrich RJ. Isotopic Dependence of the Hydrogen-Transfer-Triggered Methyl-Group Rotation in Deuterated 5-Methyltropolone. J Mol Spectrosc 2018; 343:10.1016/j.jms.2017.09.004. [PMID: 31097843 PMCID: PMC6512845 DOI: 10.1016/j.jms.2017.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We present here the first experimental study of the microwave spectrum of deuterated 5-methyltropolone, a molecule which exhibits two large-amplitude motions: an intramolecular hydrogen transfer (deuterium transfer in the current case of deuterated 5-methyltropolone) and a methyl torsion. The main goal of this study was to get information on the isotopic dependence of the main tunneling parameters of 5-methyltropolone in the framework of the two dimensional tunneling formalism, which previously has shown some counterintuitive results for isotopic dependence of tunneling parameters in 2-methylmalonaldehyde. Measurements were carried out by Fourier-transform microwave spectroscopy in the 9 GHz to 26 GHz frequency range. Theoretical analysis was carried out using a tunneling-rotational Hamiltonian based on a G12 m extended-group-theory formalism. Our global fit of 384 transitions to 17 molecular parameters gave a weighted root-mean-square deviation of 0.8. The current study on the isotopic dependence of the main tunneling parameters in 5-methyltropolone supports the assumption of possible "leakage" between tunneling parameters in the two-dimensional tunneling formalism in use.
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Affiliation(s)
- Vadim V Ilyushin
- Institute of Radio Astronomy of NASU, Mystetstv 4, 61002 Kharkov, Ukraine
- Quantum Radiophysics Department of V.N. Karazin Kharkiv National University, Svobody Square 4, 61022, Kharkov, Ukraine
| | - Alyssa M Johnson
- Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA
| | - Jenna Hohl
- Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA
| | - Emily A Cloessner
- Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA
| | - Frank J Lovas
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441, USA
| | - Richard J Lavrich
- Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424, USA
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Abstract
The microwave spectrum of the molecular complex of sulfur dioxide (SO2) with carbon monoxide (CO) has been studied with a pulsed-beam Fourier Transform Microwave Spectrometer (FTMW) from a pair of gas samples of 1 % by volume of SO2 and CO in Ar, and introduced via separate capillary inputs to the flow nozzle. The frequency coverage was about 7 GHz to 16 GHz for various isotopomers. The molecular structure was determined with the aid of spectral studies of isotopically substituted monomers containing 13C, 18O and 34S. The rotational analyses provide the rotational and centrifugal distortion constants for all of the isotopomers analyzed. The structure determination is compared to detailed ab initio structural calculations. The electric dipole moment components along the a- and c-axis were determined from Stark effect measurements.
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Affiliation(s)
- F J Lovas
- National Institute of Standards and Technology, Sensor Science Division, 100 Bureau Dr., Gaithersburg, MD 20899-8441
| | - M K Sprague
- National Institute of Standards and Technology, Chemical Sciences Division, 100 Bureau Dr., Gaithersburg, MD 20899-8320. Current address: St. Norbert College, 100 Grant St., De Pere, WI 54115
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Rivera-Rivera LA, Wang Z, McElmurry BA, Willaert FF, Lucchese RR, Bevan JW, Suenram RD, Lovas FJ. A ground state morphed intermolecular potential for the hydrogen bonded and van der Waals isomers in OC:HI and a prediction of an anomalous deuterium isotope effect. J Chem Phys 2011; 133:184305. [PMID: 21073221 DOI: 10.1063/1.3505145] [Citation(s) in RCA: 11] [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: 11/14/2022] Open
Abstract
An extended analysis of the noncovalent interaction OC:HI is reported using microwave and infrared supersonic jet spectroscopic techniques. All available spectroscopic data then provide the basis for generating an accurately determined vibrationally complete semiempirical intermolecular potential function using a four-dimensional potential coordinate morphing methodology. These results are consistent with the existence of four bound isomers: OC-HI, OC-IH, CO-HI, and CO-IH. Analysis also leads to unequivocal characterization of the common isotopic ground state as having the OC-HI structure and with the first excited state having the OC-IH structure with an energy of 3.4683(80) cm(-1) above the ground state. The potential is consistent with the following barriers between the pairs of isomers: 382(4) cm(-1) (OC-IH/OC-HI), 294(5) cm(-1) (CO-IH/CO-HI), 324(3) cm(-1) (OC-IH/CO-IH), and 301(2) cm(-1) (OC-HI/CO-HI) defined with respect to each lower minimum. The potential is also determined to have a linear OC-IH van der Waals global equilibrium minimum structure having R(e)=4.180(11) Å, θ(1)=0.00(1)°, and θ(2)=0.00(1)°. This is differentiated from its OC-HI ground state hydrogen bound structure having R(0)=4.895(1) Å, θ(1)=20.48(1)°, and θ(2)=155.213(1)° where the distances are defined between the centers of mass of the monomers and θ(1) and θ(2) as cos(-1)[<cos(2) θ(i)>(1/2)] for i=1 and 2. A fundamentally new molecular phenomenon - ground state isotopic isomerization is proposed based on the generated semiempirical potential. The protonated ground state hydrogen-bonded OC-HI structure is predicted to be converted on deuteration to the corresponding ground state van der Waals OC-ID isomeric structure. This results in a large anomalous isotope effect in which the R(0) center of mass distance between monomeric components changes from 4.895(1) to 4.286(1) Å. Such a proposed isotopic effect is demonstrated to be a consequence of differential zero point energy factors resulting from the shallower nature of hydrogen bonding at a local potential minimum (greater quartic character of the potential) relative to the corresponding van der Waals global minimum. Further consequences of this anomalous deuterium isotope effect are also discussed.
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Affiliation(s)
- Luis A Rivera-Rivera
- Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA
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Plusquellic DF, Kleiner I, Demaison J, Suenram RD, Lavrich RJ, Lovas FJ, Fraser GT, Ilyushin VV. The microwave spectrum of a two-top peptide mimetic: The N-acetyl alanine methyl ester molecule. J Chem Phys 2006; 125:104312. [PMID: 16999531 DOI: 10.1063/1.2348871] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The rotational spectrum of N-acetyl alanine methyl ester, a derivative of the biomimetic, N-acetyl alanine N'-methyl amide or alanine dipeptide, has been measured using a mini Fourier transform spectrometer between 9 and 25 GHz as part of a project undertaken to determine the conformational structures of various peptide mimetics from the torsion-rotation parameters of low-barrier methyl tops. Torsion-rotation splittings from two of the three methyl tops capping the acetyl end of the -NH-C(=O)- and the methoxy end of -C(=O)-O- groups account for most of the observed lines. In addition to the AA state, two E states have been assigned and include an AE state having a torsional barrier of 396.45(7) cm(-1) (methoxy rotor) and an EA state having a barrier of 64.96(4) cm(-1) (acetyl rotor). The observed torsional barriers and rotational constants of alanine dipeptide and its methyl ester are compared with predictions from Möller-Plesset second-order perturbation theory (MP2) and density functional theory (DFT) in an effort to explore systematic errors at the two levels of theory. After accounting for zero-point energy differences, the torsional barriers at the MP2/cc-pVTZ level are in excellent agreement with experiment for the acetyl and methoxy groups while DFT predictions range from 8% to 80% too high or low. DFT is found to consistently overestimate the overall molecular size while MP2 methods give structures that are undersized. Structural discrepancies of similar magnitude are evident in previous DFT results of crystalline peptides.
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Affiliation(s)
- David F Plusquellic
- Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441, USA.
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Lovas FJ, McMahon RJ, Grabow JU, Schnell M, Mack J, Scott LT, Kuczkowski RL. Interstellar Chemistry: A Strategy for Detecting Polycyclic Aromatic Hydrocarbons in Space. J Am Chem Soc 2005; 127:4345-9. [PMID: 15783216 DOI: 10.1021/ja0426239] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.6] [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
Polycyclic aromatic hydrocarbons (PAHs) have long been postulated as constituents of the interstellar gas and circumstellar disks. Observational infrared emission spectra have been plausibly interpreted in support of this hypothesis, but the small (or zero) dipole moments of planar, unsubstituted PAHs preclude their definitive radio astronomical identification. Polar PAHs, such as corannulene, thus represent important targets for radio astronomy because they offer the possibilities of confirming the existence of PAHs in space and revealing new insight into the chemistry of the interstellar medium. Toward this objective, the high-resolution rotational spectrum of corannulene has been obtained by Fourier transform microwave spectroscopy, and the dipole moment (2.07 D) of this exceptionally polar PAH has been measured by exploiting the Stark effect.
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Affiliation(s)
- F J Lovas
- Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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Abstract
Microwave spectra of Ar-(28)SiH(4), Ar-(29)SiH(4), Ar-(30)SiH(4), and Ar-(28)SiD(4) were recorded using a pulsed molecular beam Fourier transform microwave spectrometer. The K = 0 and K = 1 components of the J = 3 <-- 2 through the J = 7 <-- 6 transitions were measured and assigned in the 9-24 GHz region. For the primary (28)Si isotopic species, Ar-(28)SiH(4) and Ar-(28)SiD(4), a K = 0, A symmetry, a K = 0, F symmetry, a doubly degenerate K = 1, E symmetry, and an l/K-doubled, K = 1, F symmetry rotational progression are observed at the approximately 1 K rotational temperature of the supersonic expansion. The rotational constants for the K = 0, A state for Ar-(28)SiH(4) and Ar-(28)SiD(4) are B = 1700.40624(9) MHz and 1630.687073(22) MHz and the centrifugal distortion constants are D(J) = 29.089(3) and 20.0198(8) kHz and H(J) = -1.91(3) and -0.851(8) Hz, respectively, where type A expanded uncertainties with a coverage factor, k = 3, are given here and elsewhere. The values of the rotational constants for the K = 0, A, and F states and for the K = 1, E state are in good agreement with the infrared-determined values for Ar-(28)SiH(4). The measured linear Stark effect of the E-state transitions was analyzed to give a dipole moment of 9.24(8) x 10(-32) C. m [0.0277(2) D]. Copyright 1999 Academic Press.
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Affiliation(s)
- Y Kawashima
- Department of Applied Chemistry, Kanagawa Institute of Technology, 1030 Shimo-ogino, Atsugi, Kanagawa, 243-0292, Japan
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Lugez CL, Lovas FJ, Hougen JT, Ohashi N. Global Analysis of a-, b-, and c-Type Transitions Involving Tunneling Components of K = 0 and 1 States of the Methanol Dimer. J Mol Spectrosc 1999; 194:95-112. [PMID: 9986779 DOI: 10.1006/jmsp.1998.7767] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Spectral data on K = 0 and 1 levels of the methanol dimer available from previous and present Fourier transform microwave measurements have been interpreted globally, using a group-theoretically derived effective Hamiltonian and corresponding tunneling matrix elements to describe the splittings arising from a large number of tunneling motions. In the present work, 302 new measurements (40 K = 1-1 and 262 K = 1-0 transitions) were added to the previous data set to give a total of 584 assigned transitions with J </= 6. As a result of the rather complete K = 0, 1 data set for J </= 4, the lone-pair exchange tunneling splittings were obtained experimentally. Matrix element expansions in J(J + 1) used in the previous K = 0 formalism were modified to apply to K > 0, essentially by making a number of real coefficients complex, as required by the generalized internal-axis-method tunneling formalism. To reduce the number of adjustable parameters to an acceptable level in both the K = 0 and K = 1 effective Hamiltonians (used in separate K = 0 and K = 1 least-squares fits), a rather large number of assumptions concerning probably negligible parameters had to be made. The present fitting results should thus be considered as providing assurance of the group-theoretical line assignments as well as a nearly quantitative global interpretation of the tunneling splittings, even though they do not yet unambiguously determine the relative contributions from all 25 group-theoretically inequivalent tunneling motions in this complex, nor do they permit quantitative extrapolation to higher K levels. Copyright 1999 Academic Press.
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Affiliation(s)
- CL Lugez
- Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899
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Suenram RD, Lovas FJ, Dixon DA. Rotational Spectrum, Structure, and Electric Dipole Moment of Bis(difluoromethyl) Ether. J Mol Spectrosc 1998; 192:441-448. [PMID: 9831512 DOI: 10.1006/jmsp.1998.7713] [Citation(s) in RCA: 3] [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: 05/22/2023]
Abstract
The rotational spectrum of bis(difluoromethyl) ether (CF2HOCF2H) has been observed and analyzed using both a conventional Stark-modulated microwave spectrometer and a pulsed molecular beam Fabry-Perot cavity microwave (FTMW) spectrometer. The lowest energy conformer studied here has a (hydrogen) syn-anti conformation. The high sensitivity of the FTMW spectrometer permits observation and analysis of the 13C, 18O, and 2H isotopomers in natural abundance. The electric dipole moment was measured for the normal species and found to be µa = 5.020(7) x 10(-30) C. m [1.505(2) D], µb = 0.19(4) x 10(-30) C. m [0.056(11) D], µc = 0.48(2) x 10(-30) C. m [0.144(7) D], and µT = 5.047(10) x 10(-30) C. m [1.513(3) D].
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Affiliation(s)
- RD Suenram
- Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899
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Stone SC, Philips LA, Fraser GT, Lovas FJ, Xu LH, Sharpe SW. High-Resolution Microwave and Infrared Molecular-Beam Studies of the Conformers of 1,1,2,2-Tetrafluoroethane. J Mol Spectrosc 1998; 192:75-85. [PMID: 9770390 DOI: 10.1006/jmsp.1998.7664] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
High-resolution microwave and infrared molecular-beam spectra have been measured for 1,1,2,2-tetrafluoroethane (HFC134). For the higher energy, polar, C2 symmetry, gauche conformer, microwave spectra have been recorded for the normal and mono-13C isotopomers and analyzed to determine a C-C bond length of 1.512(4) Å, in good agreement with a recent ab initio value (MP2/6-31G**) of 1.515 Å [S. Papasavva, K. H. Illinger, and J. E. Kenny, J. Phys. Chem. 100, 10100-10110 (1996)]. A tunable microwave-sideband CO2 laser and electric-resonance optothermal spectrometer have been used to measure the infrared spectrum of the nu6, C-C stretch of the gauche conformer near 906 cm-1. Microwave-infrared double resonance and precise ground state combination differences provided by the microwave measurements guide the assignment of the spectrum. The observation of a c-type spectrum definitively establishes that the upper state vibration is of A symmetry in the C2 point group. The spectrum is fit to a Watson asymmetric-top Hamiltonian to a standard deviation of 0.24 MHz. A weak perturbation shifts the line positions for transitions near J = Kc = 20 by as much as 12 MHz. The identity of the perturber is unknown. Pulsed slit-jet diode-laser spectra have been recorded for the nu16 vibration of the anti conformer near 1127 cm-1. An a- and c-type hybrid band is observed, consistent with a Bu symmetry mode. Previous low-resolution studies have attributed the 1127-cm-1 mode to either a Bu or an Au symmetry vibration. A total of 522 nonblended transitions were assigned and fit to determine ground and excited state constants. The ground state constants of A = 5134.952(65) MHz, B = 3148.277(27) MHz, and C = 2067.106(43) MHz are the first experimental determinations of the rotational constants for this conformer. Here, type A standard uncertainties are given in the parentheses. Copyright 1998 Academic Press.
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Affiliation(s)
- SC Stone
- Department of Chemistry, Cornell University, Ithaca, New York, 14853
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Suenram RD, Lovas FJ, Quade CR, Su CF. Observation of Tunneling States within the Two Conformations of Hydroxyl gauche, Methyl Asymmetric CH2DCH2OH. J Mol Spectrosc 1998; 188:9-13. [PMID: 9480797 DOI: 10.1006/jmsp.1997.7505] [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: 05/22/2023]
Abstract
Fourier transform microwave (FTMW) spectroscopy has been used to observe and resolve the 60-kHz tunneling splitting between the symmetric and antisymmetric substates of conformations I and II for hydroxyl gauche, methyl asymmetric CH2DCH2OH. Conformation I has the hydroxyl H and methyl D on the same side of the molecular plane whereas conformation II has them on the opposite sides. The determination of the small energy difference between these two conformers leads to an improved value of Vs1s2, (the potential energy coefficient that localizes the molecule into conformations I and II) of 4.8(5) cm-1. Further, the relative intensities of the spectra show that conformation II is lower in energy than conformation I. Analysis of the quadrupole splittings of the a-type 101-000 transitions determines values for eQqaa that range from -87 to -98 kHz for both hydroxyl conformations with the methyl group asymmetric and +84 to +102 kHz for both hydroxyl conformations with the methyl group symmetric. Copyright 1998 Academic Press.
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Affiliation(s)
- RD Suenram
- Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899
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Stockman PA, Blake GA, Lovas FJ, Suenram RD. Microwave rotation-tunneling spectroscopy of the water–methanol dimer: Direct structural proof for the strongest bound conformation. J Chem Phys 1997. [DOI: 10.1063/1.474736] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.8] [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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Abstract
The rotational spectrum of (CH3OH)2 has been observed in the 8 to 24 GHz region with a pulsed-beam Fabry-Perot cavity Fourier-transform microwave spectrometer. Previously we demonstrated that each transition of the a-type R(J), Ka = 0 is split into 15 states of the 16 theoretically expected states by tunneling motions. Here we show that the K = 1 states are split into the 16 expected states through the assignment of the Ka = 1 a-type transitions and DeltaKa = 1 b-type transitions. The internal-rotation analysis of the two inequivalent methyl groups presented here was guided by the previous experimental observations and theory for multidimensional tunneling, which predicts 16 tunneling components for each R(J) transition from 25 distinct tunneling motions. The effective barrier to internal rotation for the donor methyl group of (CH3OH)2 is V3 = 183.0 cm-1, and is one-half of the value for the methanol monomer (370 cm-1), while the barrier to internal rotation of the acceptor methyl group is 120 cm-1, one-third of the methanol monomer. The structure of the methanol dimer complex is similar to that of water dimer with a hydrogen bond distance of 1.96(2) A and tilt of the acceptor methanol of 77(2)degrees from the O-H-O axis (one standard deviation uncertainty). This structure shows good agreement with the angular orientation of the methyl groups derived in the internal-rotation analysis. Copyright 1997 Academic Press. Copyright 1997Academic Press
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Affiliation(s)
- FJ Lovas
- Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899
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Xu LH, Andrews AM, Cavanagh RR, Fraser GT, Irikura KK, Lovas FJ, Grabow JU, Stahl W, Crawford MK, Smalley RJ. Rotational and Vibrational Spectroscopy and Ideal Gas Heat Capacity of HFC 134a (CF3CFH2). J Phys Chem A 1997. [DOI: 10.1021/jp9640383] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lovas FJ, Fowler PW, Kisiel Z, Tseng S, Beck RD, Eggers DF, Blake TA, Watts RO. The structures of CO–CH3CCH and N2–CH3CCH: Spectroscopic measurements and modeling. J Chem Phys 1994. [DOI: 10.1063/1.466385] [Citation(s) in RCA: 11] [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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Kuczkowski RL, Lovas FJ, Suenram R, Lattimer RP, Hillig KW, Ashe AJ. The microwave spectrum, structure and dipole moment of 1,4-pentadiyne. J Mol Struct 1981. [DOI: 10.1016/0022-2860(81)85014-4] [Citation(s) in RCA: 14] [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: 11/30/2022]
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Lovas FJ, Suenram RD, Johnson DR, Clark FO, Tiemann E. Pyrolysis of ethylamine. II. Synthesis and microwave spectrum of ethylidenimine (CH3CH=NH). J Chem Phys 1980. [DOI: 10.1063/1.439783] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.0] [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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