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Navarro Navarrete JE, Bull JN, Cederquist H, Indrajith S, Ji M, Schmidt HT, Zettergren H, Zhu B, Stockett MH. Experimental radiative cooling rates of a polycyclic aromatic hydrocarbon cation. Faraday Discuss 2023; 245:352-367. [PMID: 37317671 DOI: 10.1039/d3fd00005b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
Several small Polycyclic Aromatic Hydrocarbons (PAHs) have been identified recently in the Taurus Molecular Cloud (TMC-1) using radio telescope observations. Reproducing the observed abundances of these molecules has been a challenge for astrochemical models. Rapid radiative cooling of PAHs by Recurrent Fluorescence (RF), the emission of optical photons from thermally populated electronically excited states, has been shown to efficiently stabilize small PAHs following ionization, augmenting their resilience in astronomical environments and helping to rationalize their observed high abundances. Here, we use a novel method to experimentally determine the radiative cooling rate of the cation of 1-cyanonaphthalene (C10H7CN, 1-CNN), the neutral species of which has been identified in TMC-1. Laser-induced dissociation rates and kinetic energy release distributions of 1-CNN cations isolated in a cryogenic electrostatic ion-beam storage ring are analysed to track the time evolution of the vibrational energy distribution of the initially hot ion ensemble as it cools. The measured cooling rate is in good agreement with the previously calculated RF rate coefficient. Improved measurements and models of the RF mechanism are needed to interpret astronomical observations and refine predictions of the stabilities of interstellar PAHs.
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Affiliation(s)
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich, UK
| | | | | | - MingChao Ji
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | | | | | - Boxing Zhu
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | - Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden.
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Zhu B, Bull JN, Ji M, Zettergren H, Stockett MH. Radiative cooling rates of substituted PAH ions. J Chem Phys 2022; 157:044303. [DOI: 10.1063/5.0089687] [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 unimolecular dissociation and infrared radiative cooling rates of cationic 1-hydroxypyrene (OHPyr$^+$, \ce{C16H10O+}) and 1-bromopyrene (BrPyr$^+$, \ce{C16H9Br+}) are measured using a cryogenic electrostatic \rev{ion beam} storage ring. A novel numerical approach is developed to analyze the time dependence of the dissociation rate and to determine the absolute scaling of the radiative cooling rate coefficient. The model results show that radiative cooling competes with dissociation below the critical total vibrational energies \revv{$E_c=5.39(1)$}~eV for OHPyr$^+$ and \revv{5.90(1)}~eV for BrPyr$^+$. These critical energies and implications for radiative cooling dynamics are important for astrochemical models concerned with energy dissipation and molecular lifecycles. The methods presented extend the utility of storage ring experiments on astrophysically relevant ions.
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Affiliation(s)
| | - James N Bull
- School of Chemistry, University of East Anglia, United Kingdom
| | - MingChao Ji
- Stockholm University Department of Physics, Sweden
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Hansen K. DECAY DYNAMICS IN MOLECULAR BEAMS. MASS SPECTROMETRY REVIEWS 2021; 40:725-740. [PMID: 32362024 DOI: 10.1002/mas.21630] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
The phenomenon of power law decays in molecular beams is reviewed. The transition from a canonical to a microcanonical description of the decay is analyzed, and the appearance of the power law decay derived. Deviations from a power law often contain information on parallel competing processes. This is illustrated with examples where thermal radiation or dark unimolecular channels are the competing processes. Also corrections to the power law due to finite heat capacities and from nonideal energy distributions are derived. Finally, the consequences for the interpretation of action spectroscopy data are reviewed. © 2020 The Authors. Mass Spectrometry Reviews published by Wiley Periodicals, Inc. Mass Spec Rev.
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Affiliation(s)
- Klavs Hansen
- Department of Physics, School of Science, Center for Joint Quantum Studies, Tianjin University, 92 Weijin Road, 300072, Tianjin, China
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Bernard J, Al-Mogeeth A, Martin S, Montagne G, Joblin C, Dontot L, Spiegelman F, Rapacioli M. Experimental and theoretical study of photo-dissociation spectroscopy of pyrene dimer radical cations stored in a compact electrostatic ion storage ring. Phys Chem Chem Phys 2021; 23:6017-6028. [PMID: 33667290 DOI: 10.1039/d0cp05779g] [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
In this paper, we present an experimental and theoretical study of the photo-dissociation of free-flying dimer radical cations of pyrene (C16H10)2+. Experimentally, the dimers were produced in the plasma of an electron cyclotron resonance ion source and stored in an electrostatic ion storage ring, the Mini-Ring for times up to 10 ms and the photo-dissociation spectrum was recorded in the 400 to 2000 nm range. Two broad absorption bands were observed at 550 (2.25 eV) and 1560 nm (0.79 eV), respectively. Theoretical simulations of the absorption spectrum as a function of the temperature were performed using the Density Functional based Tight Binding approach within the Extended Configuration Interaction scheme (DFTB-EXCI) to determine the electronic structure. The simulation involved all excited electronic states correlated asymptotically with the five lowest excited states D1-D5 of the monomer cation and a Monte Carlo exploration of the electronic ground state potential energy surface. The simulations exhibit three major bands at 1.0, 2.1 and 2.8 eV respectively. They allow assigning the experimental band at 1560 nm to absorption by the charge resonance (CR) excited state correlated with the ground state of the monomer D0. The band at 550 nm is tentatively attributed to dimer states correlated with excited states D2-D4, in the monomer cation. Simulations also show that the CR band broadens and shifts towards longer wavelength with increasing temperature. It results from the dependence on the geometry of the energy gap between the ground state and the lowest excited state. The comparison of the experimental spectrum with theoretical spectra at various temperatures allows us to estimate the temperature of the stored (C16H10)2+ in the 300-400 K range, which is also in line with the expected temperatures of the ions deduced from the analysis of the natural decay curve.
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Affiliation(s)
- J Bernard
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France.
| | - A Al-Mogeeth
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France.
| | - S Martin
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France.
| | - G Montagne
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex, France.
| | - C Joblin
- Institut de Recherche en Astrophysique et Planétologie, Université de Toulouse (UPS), CNRS, CNES, 9 Avenue du Colonel Roche, F-31028 Toulouse, France
| | - L Dontot
- Laboratoire de Chimie et de Physique Quantiques (LCPQ), IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - F Spiegelman
- Laboratoire de Chimie et de Physique Quantiques (LCPQ), IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
| | - M Rapacioli
- Laboratoire de Chimie et de Physique Quantiques (LCPQ), IRSAMC, Université de Toulouse (UPS) and CNRS, 118 Route de Narbonne, F-31062 Toulouse, France
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Stockett MH, Bull JN, Buntine JT, Carrascosa E, Ji M, Kono N, Schmidt HT, Zettergren H. Unimolecular fragmentation and radiative cooling of isolated PAH ions: A quantitative study. J Chem Phys 2020; 153:154303. [PMID: 33092387 DOI: 10.1063/5.0027773] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Time-resolved spontaneous and laser-induced unimolecular fragmentation of perylene cations (C20H12 +) has been measured on timescales up to 2 s in a cryogenic electrostatic ion beam storage ring. We elaborate a quantitative model, which includes fragmentation in competition with radiative cooling via both vibrational and electronic (recurrent fluorescence) de-excitation. Excellent agreement with experimental results is found when sequential fragmentation of daughter ions co-stored with the parent perylene ions is included in the model. Based on the comparison of the model to experiment, we constrain the oscillator strength of the D1 → D0 emissive electronic transition in perylene (fRF = 0.055 ± 0.011), as well as the absolute absorption cross section of the D5 ← D0 excitation transition (σabs > 670 Mb). The former transition is responsible for the laser-induced and recurrent fluorescence of perylene, and the latter is the most prominent in the absorption spectrum. The vibrational cooling rate is found to be consistent with the simple harmonic cascade approximation. Quantitative experimental benchmarks of unimolecular processes in polycyclic aromatic hydrocarbon ions like perylene are important for refining astrochemical models.
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Affiliation(s)
- Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
| | - Jack T Buntine
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Eduardo Carrascosa
- Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland
| | - MingChao Ji
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Naoko Kono
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Henning T Schmidt
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
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Ferrari P, Janssens E, Lievens P, Hansen K. Radiative cooling of size-selected gas phase clusters. INT REV PHYS CHEM 2019. [DOI: 10.1080/0144235x.2019.1678929] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Piero Ferrari
- Quantum Solid State Physics, Department of Physics and Astronomy, Faculty of Science, KU Leuven, Leuven, Belgium
| | - Ewald Janssens
- Quantum Solid State Physics, Department of Physics and Astronomy, Faculty of Science, KU Leuven, Leuven, Belgium
| | - Peter Lievens
- Quantum Solid State Physics, Department of Physics and Astronomy, Faculty of Science, KU Leuven, Leuven, Belgium
| | - Klavs Hansen
- Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin, People's Republic of China
- Department of Physics, University of Gothenburg, Gothenburg, Sweden
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Chen FQ, Kono N, Suzuki R, Furukawa T, Tanuma H, Ferrari P, Azuma T, Matsumoto J, Shiromaru H, Zhaunerchyk V, Hansen K. Radiative cooling of cationic carbon clusters, C N+, N = 8, 10, 13-16. Phys Chem Chem Phys 2019; 21:1587-1596. [PMID: 30620033 DOI: 10.1039/c8cp06368k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The radiative cooling of highly excited carbon cluster cations of sizes N = 8, 10, 13-16 has been studied in an electrostatic storage ring. The cooling rate constants vary with cluster size from a maximum at N = 8 of 2.6 × 104 s-1 and a minimum at N = 13 of 4.4 × 103 s-1. The high rates indicate that photon emission takes place from electronically excited ions, providing a strong stabilizing cooling of the molecules.
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Affiliation(s)
- F-Q Chen
- School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China
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