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Hansen NA, Price TD, Filardi LR, Gurses SM, Zhou W, Hansen N, Osborn DL, Zádor J, Kronawitter CX. The photoionization of methoxymethanol: Fingerprinting a reactive C2 oxygenate in a complex reactive mixture. J Chem Phys 2024; 160:124306. [PMID: 38526109 DOI: 10.1063/5.0197827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 03/03/2024] [Indexed: 03/26/2024] Open
Abstract
Methoxymethanol (CH3OCH2OH) is a reactive C2 ether-alcohol that is formed by coupling events in both heterogeneous and homogeneous systems. It is found in complex reactive environments-for example those associated with catalytic reactors, combustion systems, and liquid-phase mixtures of oxygenates. Using tunable synchrotron-generated vacuum-ultraviolet photons between 10.0 and 11.5 eV, we report on the photoionization spectroscopy of methoxymethanol. We determine that the lowest-energy photoionization process is the dissociative ionization of methoxymethanol via H-atom loss to produce [C2H5O2]+, a fragment cation with a mass-to-charge ratio (m/z) = 61.029. We measure the appearance energy of this fragment ion to be 10.24 ± 0.05 eV. The parent cation is not detected in the energy range examined. To elucidate the origin of the m/z = 61.029 (C2H5O2) fragment, we used automated electronic structure calculations to identify key stationary points on the cation potential energy surface and compute conformer-specific microcanonical rate coefficients for the important unimolecular processes. The calculated H-atom dissociation pathway results in a [C2H5O2]+ fragment appearance at 10.21 eV, in excellent agreement with experimental results.
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Affiliation(s)
- Niko A Hansen
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
| | - Trevor D Price
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
| | - Leah R Filardi
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
| | - Sadi M Gurses
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
| | - Wenqi Zhou
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
| | - Nils Hansen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| | - David L Osborn
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| | - Judit Zádor
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| | - Coleman X Kronawitter
- Department of Chemical Engineering, University of California, Davis, California 95616, USA
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Dwivedi S, Mata J, Mushrif SH, Chaffee AL, Tanksale A. Molecular Clustering in Formaldehyde-Methanol-Water Mixtures Revealed by High-Intensity, High-q Small-Angle Neutron Scattering. J Phys Chem Lett 2021; 12:480-486. [PMID: 33373259 DOI: 10.1021/acs.jpclett.0c03515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Methanol-Water (mw) mixtures, with or without a solute, display a nonideal thermodynamic behavior, typically attributed to the structure of the microphase. However, experimental observation of the microphase structures at the molecular length scale has been a challenge. We report the presence of molecular clusters in mw and formaldehyde-methanol-water (fmw) mixtures using small-angle neutron scattering (SANS) experiments and molecular dynamics (MD) simulations. Hydrophobic clusters of methanol in mw and formaldehyde-methanol in fmw mixtures were observed at low methanol compositions (xm ≤ 0.3). A three-dimensional hydrogen-bonded network of water with the solute is observed at xm = 0.5. Linear chains of methanol surrounding the formaldehyde and water molecules were observed at high methanol compositions (xm ≥ 0.7). The calculated size of the molecular clusters (r ≈ 0.5 nm, spherical) from the SANS data and their volume fraction closely matched the MD simulation results.
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Affiliation(s)
- Swarit Dwivedi
- Department of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia
| | - Jitendra Mata
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Samir H Mushrif
- Department of Chemical and Materials Engineering, University of Alberta, 9211-116 Street, Edmonton, Alberta T6G 1H9, Canada
| | - Alan L Chaffee
- School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Akshat Tanksale
- Department of Chemical Engineering, Monash University, Clayton, Victoria 3800, Australia
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