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Raston PL, Douberly GE. Infrared Laser Stark Spectroscopy of Methyl Fluoride in 4He Nanodroplets. Chemphyschem 2024; 25:e202400224. [PMID: 38511250 DOI: 10.1002/cphc.202400224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 03/20/2024] [Accepted: 03/20/2024] [Indexed: 03/22/2024]
Abstract
We measured the rotationally resolved infrared spectra of helium solvated methyl fluoride at 3 μm and 10 μm, wherein lies C-H and C-F stretching bands, respectively. The linewidths (FWHM) were found to increase with increasing vibrational energy and range from 0.002 cm-1 in the v3 band (C-F stretch) at ~1047 cm-1, to 0.65 cm-1 in the v4 band (asymmetric C-H stretch) at ~2997 cm-1. In between these two bands we observed the lower and upper components of the Fermi triad bands (ν1/2ν2/2ν5) at ~2859 and ~2961 cm-1. We carried out Stark spectroscopy on the lower band on account of its narrower linewidths (0.04 vs. 0.14 cm-1, respectively). The objective of performing Stark spectroscopy was to see if there is any evidence for a rotational linewidth dependence on the external field strength, due to a reduced difference in between methyl fluorides rotational energy gap and the roton-gap of superfluid helium. We did not find any evidence for such an effect, which we largely attribute to the rotational energy gap not increasing significantly enough by the external field. We point to another molecule (formaldehyde) whose energy levels are predicted to show a more promising response to application of an external field.
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Affiliation(s)
- Paul L Raston
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI, 96822, United States
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA, 22807, United States
| | - Gary E Douberly
- Department of Chemistry, University of Georgia, Athens, GA, 30602, United States
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2
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Asiamah M, Raston PL. Laser Spectroscopy of Helium Solvated Clusters of Methanol and Methanol-Water in the Symmetric Methyl Stretching Band. J Phys Chem A 2023; 127:946-955. [PMID: 36668688 DOI: 10.1021/acs.jpca.2c08327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mid-infrared spectra of methanol and methanol-water clusters have been investigated in the symmetric CD3 stretching band of CD3OH and CD3OD. We find that the position of this band provides a useful signature of the general type of hydrogen-bonded cluster it is associated with. Our results are consistent with those previously reported in the OH stretching region (Sulaiman, M. I.; Yang, S.; Ellis, A. M. J. Phys. Chem. A 2017, 121, 771-776) in that methanol clusters from the trimer to the pentamer are cyclic and that mixed clusters with one water molecule (and at least two methanol molecules) are also cyclic. We additionally provide evidence that the methanol trimer adopts a chair-like structure (as opposed to bowl-like), that mixed clusters with a larger number of water molecules are also cyclic, and that branched methanol clusters contribute to the depletion signal in larger methanol clusters. We performed double-hybrid DFT calculations which support these interpretations.
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Affiliation(s)
- Maameyaa Asiamah
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Paul L Raston
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia.,Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
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3
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Raston PL. Laser spectroscopy of helium solvated molecules: probing the inertial response. Phys Chem Chem Phys 2021; 23:25467-25479. [PMID: 34761773 DOI: 10.1039/d1cp04368d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Helium is the only solvent within which molecules can "freely" rotate, albeit with an increased moment of inertia relative to the gas phase. Evidence for this can be obtained by performing infrared laser spectroscopy on molecules embedded large helium clusters (nanodroplets), which often reveals rotationally resolved lines that are more closely spaced than in vacuo. The additional rotational inertia results from coupling of the helium to the molecule (rotor), and decreases in going from heavy (e.g., SF6) to light (e.g., CH4) rotors due to a partial breakdown in the adiabatic (following) approximation; faster (lighter) rotors cannot couple as well to helium since their effective interaction with helium is less anisotropic. In addition to this "mass" dependence to the coupling, there is also a time dependence to it, which shows up in the IR spectra as an asymmetry in the rovibrational lineshapes; this results from a delay in the response of helium to the change in rotational speed of the solvated molecule (when ΔJ = ±1). In this perspective we discuss the coupling between various probe molecules and helium that have been investigated by infrared laser spectroscopy in the frequency domain.
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Affiliation(s)
- Paul L Raston
- Department of Chemistry, University of Adelaide, SA 5005, Australia.,Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, USA.
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4
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Roy TK, Mani D, Schwaab G, Havenith M. A close competition between O–H⋯O and O–H⋯π hydrogen bonding: IR spectroscopy of anisole–methanol complex in helium nanodroplets. Phys Chem Chem Phys 2020; 22:22408-22416. [DOI: 10.1039/d0cp02589e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Anisole forms O–H⋯O as well O–H⋯π bound complexes with methanol.
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Affiliation(s)
- Tarun Kumar Roy
- Lehrstuhl für Physikalische Chemie II
- Ruhr-Universität Bochum
- Bochum
- Germany
| | - Devendra Mani
- Lehrstuhl für Physikalische Chemie II
- Ruhr-Universität Bochum
- Bochum
- Germany
| | - Gerhard Schwaab
- Lehrstuhl für Physikalische Chemie II
- Ruhr-Universität Bochum
- Bochum
- Germany
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie II
- Ruhr-Universität Bochum
- Bochum
- Germany
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5
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Miller I, Faulkner T, Raston PL. Laser Spectroscopy of Methanol Isotopologues in 4He Nanodroplets: Probing the Inertial Response around a Moderately Light Rotor. J Phys Chem A 2019; 123:1630-1636. [DOI: 10.1021/acs.jpca.8b12576] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Isaac Miller
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Ty Faulkner
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Paul L. Raston
- Department of Chemistry, University of Adelaide, Adelaide, SA 5005, Australia
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
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6
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Roenitz KM, Hays BM, Powers CR, McCabe MN, Smith H, Widicus Weaver SL, Shipman ST. AC Stark Effect Observed in a Microwave-Millimeter/Submillimeter Wave Double-Resonance Experiment. J Phys Chem A 2018; 122:6321-6327. [PMID: 29993251 DOI: 10.1021/acs.jpca.8b02116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Microwave-millimeter/submillimeter wave double-resonance spectroscopy has been developed with the use of technology typically employed in chirped pulse Fourier transform microwave spectroscopy and fast-sweep direct absorption (sub)millimeter-wave spectroscopy. This technique offers the high sensitivity provided by millimeter/submillimeter fast-sweep techniques with the rapid data acquisition offered by chirped pulse Fourier transform microwave spectrometers. Rather than detecting the movement of population as is observed in a traditional double-resonance experiment, instead we detected the splitting of spectral lines arising from the AC Stark effect. This new technique will prove invaluable when assigning complicated rotational spectra of complex molecules. The experimental design is presented along with the results from the double-resonance spectra of methanol as a proof-of-concept for this technique.
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Affiliation(s)
- Kevin M Roenitz
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | - Brian M Hays
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | - Carson R Powers
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | - Morgan N McCabe
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | - Houston Smith
- Department of Chemistry , Emory University , Atlanta , Georgia 30322 , United States
| | | | - Steven T Shipman
- Division of Natural Sciences , New College of Florida , Sarasota , Florida 34243 , United States
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7
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Sulaiman MI, Yang S, Ellis AM. Infrared Spectroscopy of Methanol and Methanol/Water Clusters in Helium Nanodroplets: The OH Stretching Region. J Phys Chem A 2017; 121:771-776. [DOI: 10.1021/acs.jpca.6b11170] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Media I. Sulaiman
- Department of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, U.K
| | - Shengfu Yang
- Department of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, U.K
| | - Andrew M. Ellis
- Department of Chemistry, University of Leicester, University Road, Leicester, LE1 7RH, U.K
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8
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Sadoon AM, Sarma G, Cunningham EM, Tandy J, Hanson-Heine MWD, Besley NA, Yang S, Ellis AM. Infrared Spectroscopy of NaCl(CH3OH)n Complexes in Helium Nanodroplets. J Phys Chem A 2016; 120:8085-8092. [DOI: 10.1021/acs.jpca.6b06227] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ahmed M. Sadoon
- Department
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
- Department
of Chemistry, College for Pure Sciences, University of Mosul, Mosul, Iraq
| | - Gautam Sarma
- Department
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Ethan M. Cunningham
- Department
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Jon Tandy
- Department
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | | | - Nicholas A. Besley
- School
of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Shengfu Yang
- Department
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
| | - Andrew M. Ellis
- Department
of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, United Kingdom
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10
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Hernandez FJ, Brice JT, Leavitt CM, Pino GA, Douberly GE. Infrared Spectroscopy of OH··CH3OH: Hydrogen-Bonded Intermediate Along the Hydrogen Abstraction Reaction Path. J Phys Chem A 2015; 119:8125-32. [DOI: 10.1021/acs.jpca.5b04875] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Federico J. Hernandez
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
- INFIQC,
Dpto. de Fisicoquímica, Facultad de Ciencias Químicas,
Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón. X5000HUA Córdoba, Argentina
| | - Joseph T. Brice
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | | | - Gustavo A. Pino
- INFIQC,
Dpto. de Fisicoquímica, Facultad de Ciencias Químicas,
Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Ciudad Universitaria, Pabellón. X5000HUA Córdoba, Argentina
| | - Gary E. Douberly
- Department
of Chemistry, University of Georgia, Athens, Georgia 30602, United States
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11
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Heger M, Altnöder J, Poblotzki A, Suhm MA. To π or not to π – how does methanol dock onto anisole? Phys Chem Chem Phys 2015; 17:13045-52. [DOI: 10.1039/c5cp01545f] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Supersonic jet spectroscopy reveals that methanol opts against aromatic docking onto anisole despite a very close competition.
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Affiliation(s)
- Matthias Heger
- Institut für Physikalische Chemie
- Georg-August-Universität Göttingen
- D-37077 Göttingen
- Germany
| | - Jonas Altnöder
- Institut für Physikalische Chemie
- Georg-August-Universität Göttingen
- D-37077 Göttingen
- Germany
| | - Anja Poblotzki
- Institut für Physikalische Chemie
- Georg-August-Universität Göttingen
- D-37077 Göttingen
- Germany
| | - Martin A. Suhm
- Institut für Physikalische Chemie
- Georg-August-Universität Göttingen
- D-37077 Göttingen
- Germany
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