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Wang E, Kling NG, LaForge AC, Obaid R, Pathak S, Bhattacharyya S, Meister S, Trost F, Lindenblatt H, Schoch P, Kübel M, Pfeifer T, Rudenko A, Díaz-Tendero S, Martín F, Moshammer R, Rolles D, Berrah N. Ultrafast Roaming Mechanisms in Ethanol Probed by Intense Extreme Ultraviolet Free-Electron Laser Radiation: Electron Transfer versus Proton Transfer. J Phys Chem Lett 2023; 14:4372-4380. [PMID: 37140167 DOI: 10.1021/acs.jpclett.2c03764] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultrafast H2+ and H3+ formation from ethanol is studied using pump-probe spectroscopy with an extreme ultraviolet (XUV) free-electron laser. The first pulse creates a dication, triggering H2 roaming that leads to H2+ and H3+ formation, which is disruptively probed by a second pulse. At photon energies of 28 and 32 eV, the ratio of H2+ to H3+ increases with time delay, while it is flat at a photon energy of 70 eV. The delay-dependent effect is ascribed to a competition between electron and proton transfer. High-level quantum chemistry calculations show a flat potential energy surface for H2 formation, indicating that the intermediate state may have a long lifetime. The ab initio molecular dynamics simulation confirms that, in addition to the direct emission, a small portion of H2 undergoes a roaming mechanism that leads to two competing pathways: electron transfer from H2 to C2H4O2+ and proton transfer from C2H4O2+ to H2.
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Affiliation(s)
- Enliang Wang
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
- Hefei National Research Center for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Nora G Kling
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
| | - Aaron C LaForge
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
| | - Razib Obaid
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
| | - Shashank Pathak
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Surjendu Bhattacharyya
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Severin Meister
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Florian Trost
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Hannes Lindenblatt
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Patrizia Schoch
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Matthias Kübel
- Institute of Optics and Quantum Electronics, Friedrich Schiller University Jena, D-07743 Jena, Germany
- Helmholtz Institute Jena, Fröbelstieg 3, 07743 Jena, Germany
| | - Thomas Pfeifer
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Artem Rudenko
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Sergio Díaz-Tendero
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Fernando Martín
- Departamento de Química, Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nano), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Robert Moshammer
- Max Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Daniel Rolles
- J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506-2604, United States
| | - Nora Berrah
- Physics Department, University of Connecticut, Storrs, Connecticut 06269-3046, United States
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Richardson V, Valença Ferreira de Aragão E, He X, Pirani F, Mancini L, Faginas-Lago N, Rosi M, Martini LM, Ascenzi D. Fragmentation of interstellar methanol by collisions with He˙ +: an experimental and computational study. Phys Chem Chem Phys 2022; 24:22437-22452. [PMID: 36102850 DOI: 10.1039/d2cp02458f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methanol is a key species in astrochemistry as its presence and reactivity provides a primary route to the synthesis of more complex interstellar organic molecules (iCOMs) that may eventually be incorporated in newly formed planetary systems. In the interstellar medium, methanol is formed by hydrogenation of CO ices on grains, and its fate upon collisions with interstellar ions should be accounted for to correctly model iCOM abundances in objects at various stages of stellar evolution. The absolute cross sections (CSs) and branching ratios (BRs) for the collisions of He˙+ ions with CH3OH are measured, as a function of the collision energy, using a Guided Ion Beam Mass Spectrometer (GIB-MS). Insights into the dissociative electron (charge) exchange mechanism have been obtained by computing the entrance and exit multidimensional Potential Energy Surfaces (PESs) and by modelling the non-adiabatic transitions using an improved Landau-Zener-Stückelberg approach. Notably, the dynamical treatment reproducing the experimental findings includes a strong orientation effect of the system formed by the small He˙+ ion and the highly polar CH3OH molecule, in the electric field gradient associated to the strongly anisotropic intermolecular interaction. This is a stereodynamical effect that plays a fundamental role in collision events occurring under a variety of conditions, with kinetic energy confined within intervals ranging from the sub-thermal to the hyper-thermal regime.
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Affiliation(s)
| | - Emília Valença Ferreira de Aragão
- Department of Chemistry, Biology and Biotechnology, Università degli studi di Perugia, Perugia, Italy.,Master-Tec s.r.l., Via Sicilia 41, Perugia, Italy
| | - Xiao He
- Department of Physics, University of Trento, Trento, Italy.
| | - Fernando Pirani
- Department of Chemistry, Biology and Biotechnology, Università degli studi di Perugia, Perugia, Italy.,Department of Civil and Environmental Engineering, Università degli studi di Perugia, Perugia, Italy
| | - Luca Mancini
- Department of Chemistry, Biology and Biotechnology, Università degli studi di Perugia, Perugia, Italy
| | - Noelia Faginas-Lago
- Department of Chemistry, Biology and Biotechnology, Università degli studi di Perugia, Perugia, Italy.,Master-Tec s.r.l., Via Sicilia 41, Perugia, Italy
| | - Marzio Rosi
- Department of Civil and Environmental Engineering, Università degli studi di Perugia, Perugia, Italy
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Thürmer S, Shinno T, Suzuki T. Valence Photoelectron Spectra of Liquid Methanol and Ethanol Measured Using He II Radiation. J Phys Chem A 2021; 125:2492-2503. [PMID: 33755491 DOI: 10.1021/acs.jpca.1c00288] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
High-resolution photoelectron (PE) spectra of liquid methanol and ethanol were measured using a liquid microjet and He IIα radiation (40.813 eV). The vertical ionization energy and the ionization threshold were determined as 9.70 ± 0.07 and 8.69 ± 0.07 eV for methanol and 9.52 ± 0.07 and 8.52 ± 0.07 eV for ethanol, respectively. Individual photoemission bands observed for the liquids are well correlated with those in PE spectra of the gaseous samples also measured in the present study, except that the liquid band positions were shifted on average by -1.23 eV for methanol and -1.10 eV for ethanol as compared to the gas. The 5a' and 7a' bands of liquid methanol exhibit specifically larger broadening than other bands, for which we attempted spectral fitting with two components, similarly with the case of the 3a1 band of liquid water. PE spectra of both liquid and gaseous ethanol are congested partly due to the presence of the trans and gauche isomers; however, the overall band positions are generally in good agreement with predictions based on quantum chemical calculations. Comparison of the measured PE spectra with experimental and simulated X-ray emission spectra indicate that spectral differences in the lowest ionization band of both methanol and ethanol originate from involvement of nuclear dynamics in the X-ray emission process.
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Affiliation(s)
- Stephan Thürmer
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8501, Japan
| | - Takatoshi Shinno
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8501, Japan
| | - Toshinori Suzuki
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo, Kyoto 606-8501, Japan
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