1
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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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2
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Lee JWL, Stockett MH, Ashworth EK, Navarro Navarrete JE, Gougoula E, Garg D, Ji M, Zhu B, Indrajith S, Zettergren H, Schmidt HT, Bull JN. Cooling dynamics of energized naphthalene and azulene radical cations. J Chem Phys 2023; 158:2887564. [PMID: 37125715 DOI: 10.1063/5.0147456] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 04/12/2023] [Indexed: 05/02/2023] Open
Abstract
Naphthalene and azulene are isomeric polycyclic aromatic hydrocarbons (PAHs) and are topical in the context of astrochemistry due to the recent discovery of substituted naphthalenes in the Taurus Molecular Cloud-1 (TMC-1). Here, the thermal- and photo-induced isomerization, dissociation, and radiative cooling dynamics of energized (vibrationally hot) naphthalene (Np+) and azulene (Az+) radical cations, occurring over the microsecond to seconds timescale, are investigated using a cryogenic electrostatic ion storage ring, affording "molecular cloud in a box" conditions. Measurement of the cooling dynamics and kinetic energy release distributions for neutrals formed through dissociation, until several seconds after hot ion formation, are consistent with the establishment of a rapid (sub-microsecond) Np+ ⇌ Az+ quasi-equilibrium. Consequently, dissociation by C2H2-elimination proceeds predominantly through common Az+ decomposition pathways. Simulation of the isomerization, dissociation, recurrent fluorescence, and infrared cooling dynamics using a coupled master equation combined with high-level potential energy surface calculations [CCSD(T)/cc-pVTZ], reproduce the trends in the measurements. The data show that radiative cooling via recurrent fluorescence, predominately through the Np+ D0 ← D2 transition, efficiently quenches dissociation for vibrational energies up to ≈1 eV above dissociation thresholds. Our measurements support the suggestion that small cations, such as naphthalene, may be more abundant in space than previously thought. The strategy presented in this work could be extended to fingerprint the cooling dynamics of other PAH ions for which isomerization is predicted to precede dissociation.
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Affiliation(s)
- Jason W L Lee
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Mark H Stockett
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Eleanor K Ashworth
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | | | - Eva Gougoula
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Diksha Garg
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - MingChao Ji
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Boxing Zhu
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | | | | | - Henning T Schmidt
- Department of Physics, Stockholm University, SE-10691 Stockholm, Sweden
| | - James N Bull
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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3
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Hansen K, Licht O, Kurbanov A, Toker Y. Cascade Infrared Thermal Photon Emission. J Phys Chem A 2023; 127:2889-2894. [PMID: 36966418 DOI: 10.1021/acs.jpca.2c09024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2023]
Abstract
The later stages of cooling of molecules and clusters in the interstellar medium are dominated by emission of vibrational infrared radiation. With the development of cryogenic storage it has become possible to experimentally study these processes. Recent storage ring results demonstrate that intramolecular vibrational redistribution takes place within the cooling process, and an harmonic cascade model has been used to interpret the data. Here we analyze this model and show that the energy distributions and the photon emission rates develop into near-universal functions that can be characterized with only a few parameters, irrespective of the precise vibrational spectra and oscillator strengths of the systems. We show that the photon emission rate and emitted power vary linearly with total excitation energy with a small offset. The time developments of ensemble internal energy distributions are calculated with respect to their first two moments. The excitation energy decreases exponentially with a rate constant which is the average of all k1→0 Einstein coefficients, and the time development of the variance is also calculated.
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Affiliation(s)
- Klavs Hansen
- Lanzhou Center for Theoretical Physics, Key Laboratory of Theoretical Physics of Gansu Province, Lanzhou University, Lanzhou, Gansu 730000, China
- Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, 92 Weijin Road, Tianjin 300072, China
| | - Ori Licht
- Department of Physics and Institute for Nanotechnology and Advanced Materials, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Adeliya Kurbanov
- Department of Physics and Institute for Nanotechnology and Advanced Materials, Bar Ilan University, Ramat-Gan 5290002, Israel
| | - Yoni Toker
- Department of Physics and Institute for Nanotechnology and Advanced Materials, Bar Ilan University, Ramat-Gan 5290002, Israel
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4
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Stockett MH, Bull JN, Cederquist H, Indrajith S, Ji M, Navarro Navarrete JE, Schmidt HT, Zettergren H, Zhu B. Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds. Nat Commun 2023; 14:395. [PMID: 36693859 PMCID: PMC9873784 DOI: 10.1038/s41467-023-36092-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/13/2023] [Indexed: 01/25/2023] Open
Abstract
After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud (TMC-1) is six orders of magnitude higher than expected from astrophysical modeling. Here, we report unimolecular dissociation and radiative cooling rate coefficients of the 1-CNN isomer in its cationic form. These results are based on measurements of the time-dependent neutral product emission rate and kinetic energy release distributions produced from an ensemble of internally excited 1-CNN+ studied in an environment similar to that in interstellar clouds. We find that Recurrent Fluorescence - radiative relaxation via thermally populated electronic excited states - efficiently stabilizes 1-CNN+, owing to a large enhancement of the electronic transition probability by vibronic coupling. Our results help explain the anomalous abundance of CNN in TMC-1 and challenge the widely accepted picture of rapid destruction of small PAHs in space.
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Affiliation(s)
- Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich, United Kingdom
| | | | | | - MingChao Ji
- Department of Physics, Stockholm University, Stockholm, Sweden
| | | | | | | | - Boxing Zhu
- Department of Physics, Stockholm University, Stockholm, Sweden
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5
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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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6
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Grieser M, Schmidt VC, Blaum K, Grussie F, von Hahn R, Kálosi Á, Kreckel H, Müll D, Novotný O, Nuesslein F, Wolf A. Isochronous mass spectrometry in an electrostatic storage ring. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:063302. [PMID: 35777995 DOI: 10.1063/5.0090131] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/18/2022] [Indexed: 06/15/2023]
Abstract
For sensitive studies of molecular ions in electrostatic storage rings, the exact knowledge of the isobaric composition of stored beams from a variety of ion sources is essential. Conventional mass-filtering techniques are often inefficient to resolve the beam components. Here, we report the first isochronous mass spectrometry in an electrostatic storage ring, which offers a high mass resolution of Δm/m < 1 × 10-5 even for heavy molecular species with m > 100 u and uncooled ion beams. Mass contaminations can be resolved and identified at relative fractions down to 0.02%.
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Affiliation(s)
- Manfred Grieser
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Viviane C Schmidt
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Klaus Blaum
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Florian Grussie
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Robert von Hahn
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Ábel Kálosi
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Holger Kreckel
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Damian Müll
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Oldřich Novotný
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Felix Nuesslein
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - Andreas Wolf
- Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
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7
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Zinck N, Bodi A, Mayer PM. VUV photoprocessing of oxygen-containing polycyclic aromatic hydrocarbons: iPEPICO study of the unimolecular dissociation of ionized benzofuran. CAN J CHEM 2022. [DOI: 10.1139/cjc-2022-0062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) are potential contributors to the 11.3 m band in interstellar observations. To further explore their role in the interstellar medium, we have investigated their fate after photoprocessing by VUV radiation; in particular, we studied the dissociative photoionization of the simplest OPAH, benzofuran, with imaging photoelectron photoion coincidence spectroscopy, iPEPICO. Ionized benzofuran dissociates by loss of CO, followed by a sequential H atom loss. The parallel HCO-loss channel, leading to the same bicyclic C7H5+ fragment ion, is not competitive at low excess energies above the ionization threshold. However, the collision-induced dissociation tandem mass spectrometry results suggest that CO and HCO may be formed in parallel at higher energies. An RRKM fragmentation model reproduced the iPEPICO data well assuming the initial 1,2-H shift transition state to be rate determining to CO loss. The breakdown diagram and the measured dissociation rates agreed well at the CBS-QB3-calculated activation energy of 2.99 eV, which could be relaxed to 3.25 eV, and only a slight adjustment of the ab initio activation entropy. The model barrier to sequential H-loss is larger than the computed H-loss threshold and the breakdown diagram rises less steeply than predicted, which indicates suprastatistical kinetic energy release after the tight H-transfer transition state of the first step. HCO cleavage is possible after a ring-opening transition state, which is looser than and isoenergetic with the CO-loss transition state. However, a subsequent ring formation transition state at 3.85 eV is moderately tight, which suppresses HCO loss at low excess energies.
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Affiliation(s)
- Nicholas Zinck
- University of Ottawa, 6363, Chemistry and Biomolecular Sciences, Ottawa, Ontario, Canada
| | - Andras Bodi
- Paul Scherrer Institut PSI, 28498, Laboratory for Synchrotron Radiation and Femtochemistry, Villigen, Aargau, Switzerland
| | - Paul M Mayer
- University of Ottawa, 6363, Chemistry and Biomolecular Sciences, Ottawa, Ontario, Canada,
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8
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Stockett MH, Bull JN, Schmidt HT, Zettergren H. Statistical vibrational autodetachment and radiative cooling rates of para-benzoquinone. Phys Chem Chem Phys 2022; 24:12002-12010. [PMID: 35535575 DOI: 10.1039/d2cp00490a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We report measurements of the statistical vibrational autodetachment (VAD, also called thermionic emission) and radiative cooling rates of isolated para-benzoquinone (pBQ, C6H4O2) radical anions using the cryogenic electrostatic ion storage ring facility DESIREE. The results are interpreted using master equation simulations with rate coefficients calculated using statistical detailed balance theory. The VAD rate is determined by measuring the time-dependent yield of neutral pBQ due to spontaneous electron emission from a highly-excited ensemble of anions formed in an electron-attachment ion source. Competition with radiative cooling quenches the VAD rate after a critical time of τc = 11.00(5) ms. Master equation simulations which reproduce the VAD yield provide an estimate of the initial effective vibrational temperature of the ions of 1100(20) K, and provide insight into the anion formation scenario. A second measurement of the radiative cooling rate of pBQ- stored for up to 0.5 s was achieved using time-dependent photodetachment action spectroscopy across the 2Au ← 2B2g and 2B2u ← 2B2g transitions. The rate at which hot-band contributions fade from the action spectrum is quantified by non-negative matrix factorisation. This is found to be commensurate with the average vibrational energy extracted from the simulations, with 1/e lifetimes of 0.16(3) s and 0.1602(7) s, respectively. Implications for astrochemistry are discussed.
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Affiliation(s)
- Mark H Stockett
- Department of Physics, Stockholm University, Stockholm, Sweden.
| | - James N Bull
- School of Chemistry, University of East Anglia, Norwich, UK
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9
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Lacinbala O, Calvo F, Dubosq C, Falvo C, Parneix P, Rapacioli M, Simon A, Pino T. Radiative relaxation in isolated large carbon clusters: Vibrational emission versus recurrent fluorescence. J Chem Phys 2022; 156:144305. [DOI: 10.1063/5.0080494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recurrent fluorescence (RF) from isolated carbon clusters containing between 24 and 60 atoms is theoretically investigated as a function of internal energy, cluster size, and structural features. The vibrational relaxation kinetics and the associated IR emission spectra are determined by means of a Monte Carlo approach with vibrational density of states computed in the harmonic approximation. RF is generally found to be highly competitive with vibrational emission. The behaviors predicted for clusters of various sizes and archetypal structures indicate that the IR emission spectra are strongly influenced by RF, an energy gap law being obtained for the evolution of the RF rate constant depending on the electronic excitation state. The present results are relevant to the photophysics of the interstellar medium and could contribute to elucidating the carriers of the extended red emission bands and the continuum emission lying below the aromatic infrared bands believed to originate from mixed aromatic–aliphatic compounds.
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Affiliation(s)
- O. Lacinbala
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
| | - F. Calvo
- Université Grenoble-Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | - C. Dubosq
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - C. Falvo
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
- Université Grenoble-Alpes, CNRS, LIPhy, 38000 Grenoble, France
| | - P. Parneix
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
| | - M. Rapacioli
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - A. Simon
- Laboratoire de Chimie et Physique Quantiques (LCPQ), Fédération FeRMI, Université de Toulouse, CNRS, 31062 Toulouse, France
| | - T. Pino
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d’Orsay (ISMO), 91405 Orsay, France
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10
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Ceriotti M, Jensen L, Manolopoulos DE, Martinez TJ, Michaelides A, Ogilvie JP, Reichman DR, Shi Q, Straub JE, Vega C, Wang LS, Weiss E, Zhu X, Stein JL, Lian T. 2020 JCP Emerging Investigator Special Collection. J Chem Phys 2021; 155:230401. [PMID: 34937385 DOI: 10.1063/5.0078934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Michele Ceriotti
- Laboratory of Computational Science and Modeling, Institute of Materials, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Lasse Jensen
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - David E Manolopoulos
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Todd J Martinez
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Angelos Michaelides
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Jennifer P Ogilvie
- Department of Physics and Biophysics, University of Michigan, 450 Church St., Ann Arbor, Michigan 48109, USA
| | - David R Reichman
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | - Qiang Shi
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China; and Physical Science Laboratory, Huairou National Comprehensive Science Center, Beijing 101407, China
| | - John E Straub
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Carlos Vega
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Lai-Sheng Wang
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA
| | - Emily Weiss
- Departments of Chemistry, Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Xiaoyang Zhu
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | | | - Tianquan Lian
- Department of Chemistry, Emory University, Atlanta, Georgia 30322, USA
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