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Loreau J, van der Avoird A. Vibrational energy transfer in ammonia-helium collisions. Faraday Discuss 2024; 251:249-261. [PMID: 38787637 DOI: 10.1039/d3fd00180f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
While the rotational energy transfer of ammonia by rare gas atoms and hydrogen molecules has been the focus of many studies, little is known about its vibrational relaxation, even though transitions involving the umbrella bending mode have been observed in many astrophysical environments. Here we explore the vibrational relaxation of the umbrella mode of ammonia induced by collisions with helium atoms by means of the close-coupling method on an ab initio potential energy surface. We compute cross sections up to kinetic energies of 1500 cm-1 and rate coefficients up to a temperature of 300 K for vibrational, rotational, and inversion transitions involving the lowest two vibrational states. We show that vibrational relaxation is much less efficient than rotation-inversion relaxation, although the rate coefficients for vibrational relaxation strongly increase with the temperature. We also observe important differences for vibrationally-elastic transitions within the lowest two vibrational states, i.e., for rotation-inversion transitions. These are a direct consequence of the difference in the tunnelling splitting of the lowest inversion levels.
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Affiliation(s)
- Jérôme Loreau
- KU Leuven, Department of Chemistry, B-3001 Leuven, Belgium.
| | - Ad van der Avoird
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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Chawananon S, Asselin P, Claus JA, Goubet M, Roucou A, Georges R, Sobczuk J, Bracquart C, Pirali O, Cuisset A. Rovibrational Spectroscopy of Trans and Cis Conformers of 2-Furfural from High-Resolution Fourier Transform and QCL Infrared Measurements. Molecules 2023; 28:molecules28104165. [PMID: 37241905 DOI: 10.3390/molecules28104165] [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: 04/12/2023] [Revised: 05/11/2023] [Accepted: 05/14/2023] [Indexed: 05/28/2023] Open
Abstract
The ortho-isomer 2-furfural (2-FF), which is a primary atmospheric pollutant produced from biomass combustion, is also involved in oxidation processes leading to the formation of secondary organic aerosols. Its contribution to radiative forcing remains poorly understood. Thus, monitoring 2-FF directly in the atmosphere or in atmospheric simulation chambers to characterize its reactivity is merited. The present study reports an extensive jet-cooled rovibrational study of trans and cis conformers of 2-FF in the mid-IR region using two complementary setups: a continuous supersonic jet coupled to a high-resolution Fourier transform spectrometer on the IR beamline of the SOLEIL synchrotron (JET-AILES), and a pulsed jet coupled to a mid-IR tunable quantum cascade laser spectrometer (SPIRALES). Firstly, jet-cooled spectra recorded at rotational temperatures ranging between 20 and 50 K were exploited to derive reliable excited-state molecular parameters of trans- and cis-2-FF vibrational bands in the fingerprint region. The parameters were obtained from global fits of 11,376 and 3355 lines distributed over eight and three vibrational states (including the ground state), respectively, with a root mean square of 12 MHz. In a second step, the middle resolution spectrum of 2-FF recorded at 298.15 K and available in the HITRAN database was reconstructed by extrapolating the data derived from our low-temperature high-resolution analyses to determine the cross sections of each vibrational band of both 2-FF conformers in the 700-1800 cm-1 region. Finally, we clearly demonstrated that the contribution of hot bands observed in the room temperature 2-FF spectrum, estimated between 40 and 63% of the fundamental band, must be imperatively introduced in our simulation to correctly reproduce the HITRAN vibrational cross sections of 2-FF with a deviation smaller than 10%.
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Affiliation(s)
- Sathapana Chawananon
- Sorbonne Université, MONARIS, CNRS, UMR8233, 4 Pl Jussieu, F-75005 Paris, France
| | - Pierre Asselin
- Sorbonne Université, MONARIS, CNRS, UMR8233, 4 Pl Jussieu, F-75005 Paris, France
| | - Jordan A Claus
- Université de Lille, CNRS, UMR8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France
| | - Manuel Goubet
- Université de Lille, CNRS, UMR8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France
| | - Anthony Roucou
- Université du Littoral Côte d'Opale, UR4493, LPCA, Laboratoire de Physico-Chimie de l'Atmosphère, F-59140 Dunkerque, France
| | - Robert Georges
- Université de Rennes, CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, F-35000 Rennes, France
| | - Joanna Sobczuk
- Smoluchowski Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków, Poland
| | - Colwyn Bracquart
- Université de Lille, CNRS, UMR8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France
- Université du Littoral Côte d'Opale, UR4493, LPCA, Laboratoire de Physico-Chimie de l'Atmosphère, F-59140 Dunkerque, France
| | - Olivier Pirali
- Université de Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, F-91405 Orsay, France
| | - Arnaud Cuisset
- Université du Littoral Côte d'Opale, UR4493, LPCA, Laboratoire de Physico-Chimie de l'Atmosphère, F-59140 Dunkerque, France
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CHAWANANON S, Pirali O, Goubet M, ASSELIN P. Characterizing centrosymmetric two-ring PAHs using jet-cooled high resolution mid-infrared laser spectroscopy and anharmonic Quantum Chemical calculations. J Chem Phys 2022; 157:064301. [DOI: 10.1063/5.0096777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The presence of Polycyclic Aromatic Hydrocarbons (PAH) molecules in the interstellar medium, recently confirmed by the detection of cyano-naphthalenes, renews the interest of extensive spectroscopic and physical-chemistry studies about such large species. The present study reports the jet-cooled rovibrational IR study of three centrosymmetric two-ring PAH molecules, naphthalene (C10H8), [1,5] naphthyridine (C8H6N2) and biphenyl (C12H10) in the in-plane ring C-H bending (975-1035 cm-1) and C-C ring stretching (1580-1620 cm-1) regions. For the two most rigid PAHs, the accuracy of spectroscopic parameters derived in ground and several excited states (6 for naphthalene and 6 for [1,5] naphthyridine) has significantly improved the literature values. In addition, comparison between experiments and quantum chemical calculations confirms the predictive power of the corrected calculated rotational parameters. The more flexible structure of biphenyl makes particularly challenging the analysis of high resolution jet-cooled spectra of n19 and n23 modes recorded at about 1601 and 1013 cm-1 respectively. The presence of three torsional vibrations below 120 cm-1 together with small values of the rotational constants prevented us to determine the ground and v19=1 excited rotational constants independently. In the n23 band region, the presence of two bands rotationally resolved and separated by only 0.8 cm-1, raises the question of possible splittings due to a large amplitude motion, most probably the torsion of the aliphatic bond between the two phenyl rings.
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