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Hirsch F, Flock M, Fischer I, Bakels S, Rijs AM. The Gas-Phase Infrared Spectra of Xylyl Radicals. J Phys Chem A 2019; 123:9573-9578. [PMID: 31593463 DOI: 10.1021/acs.jpca.9b09153] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The three isomers of the xylyl radical, C8H9, are possible intermediates in the formation of soot and polycyclic aromatic hydrocarbons (PAH). Their infrared spectra have been recorded by IR/UV ion dip spectroscopy using free electron laser radiation. The radicals were generated by flash pyrolysis from the corresponding nitrites and resonantly ionized via the D3 ← D0 transition around 310 nm. Mid-infrared spectra of the three xylyl isomers were recorded between 550 and 1700 cm-1 and are in excellent agreement with computations, provided that overtones and combination bands are included in the simulation. The results show that the three xylyl isomers can be distinguished by their infrared spectra and that no isomerization occurs in the pyrolysis reactor. The IR spectra obtained at m/z = 208 indicate that dimerization of xylyl radicals leads to substituted stilbenes, which has not been observed for benzyl.
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Affiliation(s)
- Florian Hirsch
- Institute of Physical and Theoretical Chemistry , University of Wuerzburg , Am Hubland Süd, 97074 Würzburg , Germany
| | - Marco Flock
- Institute of Physical and Theoretical Chemistry , University of Wuerzburg , Am Hubland Süd, 97074 Würzburg , Germany
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry , University of Wuerzburg , Am Hubland Süd, 97074 Würzburg , Germany
| | - Sjors Bakels
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory , Toernooiveld 7-c , 6525 Nijmegen , the Netherlands
| | - Anouk M Rijs
- Radboud University , Institute for Molecules and Materials, FELIX Laboratory , Toernooiveld 7-c , 6525 Nijmegen , the Netherlands
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2
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Röder A, Petersen J, Issler K, Fischer I, Mitrić R, Poisson L. Exploring the Excited-State Dynamics of Hydrocarbon Radicals, Biradicals, and Carbenes Using Time-Resolved Photoelectron Spectroscopy and Field-Induced Surface Hopping Simulations. J Phys Chem A 2019; 123:10643-10662. [DOI: 10.1021/acs.jpca.9b06346] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anja Röder
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Jens Petersen
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Kevin Issler
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Roland Mitrić
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Lionel Poisson
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette, France
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Steglich M, Knopp G, Hemberger P. How the methyl group position influences the ultrafast deactivation in aromatic radicals. Phys Chem Chem Phys 2019; 21:581-588. [DOI: 10.1039/c8cp06087h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Excited xylyl (methyl–benzyl) radical isomers have been studied by femtosecond time-resolved photoelectron spectroscopy and mass spectrometry.
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Affiliation(s)
| | - Gregor Knopp
- Paul Scherrer Institute
- CH-5232 Villigen-PSI
- Switzerland
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Hirsch F, Constantinidis P, Fischer I, Bakels S, Rijs AM. Dimerization of the Benzyl Radical in a High-Temperature Pyrolysis Reactor Investigated by IR/UV Ion Dip Spectroscopy. Chemistry 2018. [PMID: 29528193 DOI: 10.1002/chem.201800852] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We investigate the self-reaction of benzyl, C7 H7 , in a high-temperature pyrolysis reactor. The work is motivated by the observation that resonance-stabilized benzyl radicals can accumulate in reactive environments and contribute to the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. Reaction products are detected by IR/UV ion dip spectroscopy, using infrared radiation from the free electron laser FELIX, and are identified by comparison with computed spectra. Among the reaction products identified by their IR absorption are several PAHs linked to toluene combustion such as bibenzyl, phenanthrene, diphenylmethane, and fluorene. The identification of 9,10-dihydrophenanthrene provides evidence for a mechanism of phenanthrene formation from bibenzyl that proceeds by initial cyclization rather than an initial hydrogen loss to stilbene.
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Affiliation(s)
- Florian Hirsch
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland Süd, 97074, Würzburg, Germany
| | - Philipp Constantinidis
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland Süd, 97074, Würzburg, Germany
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland Süd, 97074, Würzburg, Germany
| | - Sjors Bakels
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7-c, 6525 ED, Nijmegen, The Netherlands
| | - Anouk M Rijs
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7-c, 6525 ED, Nijmegen, The Netherlands
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Steglich M, Bodi A, Maier JP, Hemberger P. Probing different spin states in xylyl radicals and ions. Phys Chem Chem Phys 2018; 20:7180-7189. [PMID: 29480313 DOI: 10.1039/c7cp08466h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Resonant one-color two-photon ionization spectroscopy and mass-selected threshold photoelectron spectroscopy were applied to study the electronic doublet states of the three xylyl (methyl-benzyl) radicals above 3.9 eV as well as the singlet and triplet states of the cations up to 10.5 eV. The experiments are complemented by quantum chemical calculations and Franck-Condon simulations to characterize the transitions and to identify the origin bands, allowing a precise determination of singlet-triplet splittings in the cations. Torsional motions of the methyl group notably affect the D0 → D3 transition of m-xylyl. All other investigated transitions either lead to electronic states with very low rotational barriers or suffer from spectral broadening in excess of methyl torsional energy levels. The methyl internal rotational potential is faithfully reproduced with the most basic ab initio methods, yet hyperconjugation could not be identified as a significant force shaping them. Time-dependent density functional theory describes the excited electronic states better than wave function theory approaches, notably EOM-CCSD.
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Pachner K, Steglich M, Hemberger P, Fischer I. Photodissociation dynamics of the ortho- and para-xylyl radicals. J Chem Phys 2017; 147:084303. [DOI: 10.1063/1.4999906] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Kai Pachner
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Mathias Steglich
- Laboratory for Femtochemistry and Synchrotron Radiation, Paul Scherrer Institut (PSI), CH-5232 Villigen, Switzerland
| | - Patrick Hemberger
- Laboratory for Femtochemistry and Synchrotron Radiation, Paul Scherrer Institut (PSI), CH-5232 Villigen, Switzerland
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Röder A, Humeniuk A, Giegerich J, Fischer I, Poisson L, Mitrić R. Femtosecond time-resolved photoelectron spectroscopy of the benzyl radical. Phys Chem Chem Phys 2017; 19:12365-12374. [PMID: 28453017 DOI: 10.1039/c7cp01437f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a joint experimental and computational study of the nonradiative deactivation of the benzyl radical, C7H7, after UV excitation. Femtosecond time-resolved photoelectron imaging was applied to investigate the photodynamics of the radical. The experiments were accompanied by excited state dynamics simulations using surface hopping. Benzyl has been excited at 265 nm into the D-band (ππ*) and the dynamics was probed using probe wavelengths of 398 nm or 798 nm. At a probe wavelength of 398 nm a single time constant of around 70-80 fs was observed. When the dynamics was probed at 798 nm, a second time constant τ2 = 1.5 ps was visible, which can be attributed to further non-radiative deactivation to the lower-lying D1/D2 states.
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Affiliation(s)
- A Röder
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, D-97074 Würzburg, Germany.
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Shapero M, Cole-Filipiak NC, Haibach-Morris C, Neumark DM. Benzyl Radical Photodissociation Dynamics at 248 nm. J Phys Chem A 2015; 119:12349-56. [DOI: 10.1021/acs.jpca.5b07125] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mark Shapero
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Neil C. Cole-Filipiak
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Courtney Haibach-Morris
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Daniel M. Neumark
- Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
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Giegerich J, Fischer I. Photodissociation dynamics of fulvenallene, C7H6. Phys Chem Chem Phys 2013; 15:13162-8. [DOI: 10.1039/c3cp52274a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Nagy A, Fulara J, Garkusha I, Maier JP. On the benzylium/tropylium ion dichotomy: electronic absorption spectra in neon matrices. Angew Chem Int Ed Engl 2011; 50:3022-5. [PMID: 21404390 DOI: 10.1002/anie.201008036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Adam Nagy
- Departement Chemie, Universität Basel, Basel, Switzerland
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Nagy A, Fulara J, Garkusha I, Maier JP. On the Benzylium/Tropylium Ion Dichotomy: Electronic Absorption Spectra in Neon Matrices. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201008036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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