Gas-Phase Infrared Spectra of the C7H5 Radical and Its Bimolecular Reaction Products

Florian Hirsch; Ingo Fischer; Sjors Bakels; Anouk M. Rijs

doi:10.1021/acs.jpca.2c01228

Gas-Phase Infrared Spectra of the C7H5 Radical and Its Bimolecular Reaction Products

Florian Hirsch, Ingo Fischer, Sjors Bakels, Anouk M. Rijs

Research output: Contribution to Journal › Article › Academic › peer-review

4 Downloads (Pure)

Abstract

Resonance-stabilized radicals are considered as possible intermediates in the formation of polycyclic aromatic hydrocarbons (PAHs) in interstellar space. Here, we investigate the fulvenallenyl radical, the most stable C7H5 isomer by IR/UV ion dip spectroscopy employing free electron laser radiation in the mid-infrared region between 550 and 1750 cm–1. The radical is generated by pyrolysis from phthalide. Various jet-cooled reaction products are identified by their mass-selective IR spectra in the fingerprint region, based on a comparison with computed spectra. Interestingly, benzyl is present as a second resonance-stabilized radical. It is connected to fulvenallenyl by a sequence of two H atom losses or additions. Among the identified aromatic hydrocarbons are toluene and styrene, as well as polycyclic molecules, such as indene, naphthalene, fluorene and phenanthrene. Mechanisms for the formation of PAH from C7H5 have already been suggested in previous computational work. In particular, the radical/radical reaction of two fulvenallenyl radicals provides an efficient route to phenanthrene in one bimolecular step and might be relevant for PAH formation under astrochemical conditions.

Original language	English
Pages (from-to)	2532-2540
Number of pages	9
Journal	The Journal of Physical Chemistry A
Volume	126
Issue number	16
Early online date	15 Apr 2022
DOIs	https://doi.org/10.1021/acs.jpca.2c01228
Publication status	Published - 28 Apr 2022
Externally published	Yes

Bibliographical note

Published as part of The Journal of Physical Chemistry virtual special issue “10 Years of the ACS PHYS Astrochemistry Subdivision”

Funding

This work was financially supported by the Deutsche Forschungsgemeinschaft, Research Training School GRK 2112 \u201CMolecular Biradicals\u201D. Furthermore, the research leading to these results has received funding from LASERLAB EUROPE (Grant Agreement No. 871124, European Union\u2019s Horizon 2020 research and innovation programme). We gratefully thank the FELIX staff for their experimental support, and we acknowledge the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO) for the support of the FELIX Laboratory. We would also like to thank Kai Pachner for assistance in the experiments.

Funders	Funder number
Research Training School	GRK 2112
Horizon 2020 Framework Programme	871124
Deutsche Forschungsgemeinschaft

Access to Document

10.1021/acs.jpca.2c01228

hirsch-et-al-2022-gas-phase-infrared-spectra-of-the-c7h5-radical-and-its-bimolecular-reaction-productsFinal published version, 2.72 MBLicence: Article 25fa Dutch Copyright Act

Persistent URL (handle)

Persistent link

Cite this

@article{9baccdc0262349fcba96c3d34ebfa70e,

title = "Gas-Phase Infrared Spectra of the C7H5 Radical and Its Bimolecular Reaction Products",

abstract = "Resonance-stabilized radicals are considered as possible intermediates in the formation of polycyclic aromatic hydrocarbons (PAHs) in interstellar space. Here, we investigate the fulvenallenyl radical, the most stable C7H5 isomer by IR/UV ion dip spectroscopy employing free electron laser radiation in the mid-infrared region between 550 and 1750 cm–1. The radical is generated by pyrolysis from phthalide. Various jet-cooled reaction products are identified by their mass-selective IR spectra in the fingerprint region, based on a comparison with computed spectra. Interestingly, benzyl is present as a second resonance-stabilized radical. It is connected to fulvenallenyl by a sequence of two H atom losses or additions. Among the identified aromatic hydrocarbons are toluene and styrene, as well as polycyclic molecules, such as indene, naphthalene, fluorene and phenanthrene. Mechanisms for the formation of PAH from C7H5 have already been suggested in previous computational work. In particular, the radical/radical reaction of two fulvenallenyl radicals provides an efficient route to phenanthrene in one bimolecular step and might be relevant for PAH formation under astrochemical conditions.",

author = "Florian Hirsch and Ingo Fischer and Sjors Bakels and Rijs, \{Anouk M.\}",

note = "Published as part of The Journal of Physical Chemistry virtual special issue “10 Years of the ACS PHYS Astrochemistry Subdivision”",

year = "2022",

month = apr,

day = "28",

doi = "10.1021/acs.jpca.2c01228",

language = "English",

volume = "126",

pages = "2532--2540",

journal = "The Journal of Physical Chemistry A",

issn = "1089-5639",

publisher = "American Chemical Society",

number = "16",

}

TY - JOUR

T1 - Gas-Phase Infrared Spectra of the C7H5 Radical and Its Bimolecular Reaction Products

AU - Hirsch, Florian

AU - Fischer, Ingo

AU - Bakels, Sjors

AU - Rijs, Anouk M.

N1 - Published as part of The Journal of Physical Chemistry virtual special issue “10 Years of the ACS PHYS Astrochemistry Subdivision”

PY - 2022/4/28

Y1 - 2022/4/28

N2 - Resonance-stabilized radicals are considered as possible intermediates in the formation of polycyclic aromatic hydrocarbons (PAHs) in interstellar space. Here, we investigate the fulvenallenyl radical, the most stable C7H5 isomer by IR/UV ion dip spectroscopy employing free electron laser radiation in the mid-infrared region between 550 and 1750 cm–1. The radical is generated by pyrolysis from phthalide. Various jet-cooled reaction products are identified by their mass-selective IR spectra in the fingerprint region, based on a comparison with computed spectra. Interestingly, benzyl is present as a second resonance-stabilized radical. It is connected to fulvenallenyl by a sequence of two H atom losses or additions. Among the identified aromatic hydrocarbons are toluene and styrene, as well as polycyclic molecules, such as indene, naphthalene, fluorene and phenanthrene. Mechanisms for the formation of PAH from C7H5 have already been suggested in previous computational work. In particular, the radical/radical reaction of two fulvenallenyl radicals provides an efficient route to phenanthrene in one bimolecular step and might be relevant for PAH formation under astrochemical conditions.

AB - Resonance-stabilized radicals are considered as possible intermediates in the formation of polycyclic aromatic hydrocarbons (PAHs) in interstellar space. Here, we investigate the fulvenallenyl radical, the most stable C7H5 isomer by IR/UV ion dip spectroscopy employing free electron laser radiation in the mid-infrared region between 550 and 1750 cm–1. The radical is generated by pyrolysis from phthalide. Various jet-cooled reaction products are identified by their mass-selective IR spectra in the fingerprint region, based on a comparison with computed spectra. Interestingly, benzyl is present as a second resonance-stabilized radical. It is connected to fulvenallenyl by a sequence of two H atom losses or additions. Among the identified aromatic hydrocarbons are toluene and styrene, as well as polycyclic molecules, such as indene, naphthalene, fluorene and phenanthrene. Mechanisms for the formation of PAH from C7H5 have already been suggested in previous computational work. In particular, the radical/radical reaction of two fulvenallenyl radicals provides an efficient route to phenanthrene in one bimolecular step and might be relevant for PAH formation under astrochemical conditions.

UR - https://www.scopus.com/pages/publications/85128624055

UR - https://www.scopus.com/inward/citedby.url?scp=85128624055&partnerID=8YFLogxK

U2 - 10.1021/acs.jpca.2c01228

DO - 10.1021/acs.jpca.2c01228

M3 - Article

SN - 1089-5639

VL - 126

SP - 2532

EP - 2540

JO - The Journal of Physical Chemistry A

JF - The Journal of Physical Chemistry A

IS - 16

ER -

Gas-Phase Infrared Spectra of the C<sub>7</sub>H<sub>5</sub> Radical and Its Bimolecular Reaction Products