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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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Suresh JR, Whitener G, Theumer G, Bröcher DJ, Bauer I, Massa W, Knölker H. Synthesis and Crystal Structure of Dimorphic Dibenzo[cde,opq]rubicene. Chemistry 2019; 25:13759-13765. [PMID: 31339614 PMCID: PMC6899531 DOI: 10.1002/chem.201902915] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Indexed: 11/09/2022]
Abstract
Dibenzo[cde,opq]rubicene has been synthesized by an eight-step reaction sequence including an iron-mediated [2+2+1] cycloaddition and a flash vacuum pyrolysis as key steps. Two crystal modifications of the S-shaped, planar polycyclic aromatic hydrocarbon have been obtained and characterized by X-ray diffractometry.
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Affiliation(s)
- Joghee R. Suresh
- Fakultät ChemieTechnische Universität DresdenBergstrasse 6601069DresdenGermany
| | - Glenn Whitener
- Fakultät ChemieTechnische Universität DresdenBergstrasse 6601069DresdenGermany
| | - Gabriele Theumer
- Fakultät ChemieTechnische Universität DresdenBergstrasse 6601069DresdenGermany
| | - Dirk J. Bröcher
- Fakultät ChemieTechnische Universität DresdenBergstrasse 6601069DresdenGermany
| | - Ingmar Bauer
- Fakultät ChemieTechnische Universität DresdenBergstrasse 6601069DresdenGermany
| | - Werner Massa
- Fachbereich ChemiePhilipps-Universität MarburgHans-Meerwein-Strasse 435043MarburgGermany
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