Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating
We investigate the vacuum ultraviolet (VUV) photodynamics of gas phase 1- and 2-cyanonaphthalene and cyanobenzene, recently detected in the Taurus molecular cloud, by combining synchrotron radiation and a double imaging electron/ion coincidence setup. The high-resolution threshold photoelectron spec...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad16d9 |
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| author | Madhusree Roy Chowdhury Gustavo A. Garcia Helgi R. Hrodmarsson Jean-Christophe Loison Laurent Nahon |
| author_facet | Madhusree Roy Chowdhury Gustavo A. Garcia Helgi R. Hrodmarsson Jean-Christophe Loison Laurent Nahon |
| author_sort | Madhusree Roy Chowdhury |
| collection | DOAJ |
| description | We investigate the vacuum ultraviolet (VUV) photodynamics of gas phase 1- and 2-cyanonaphthalene and cyanobenzene, recently detected in the Taurus molecular cloud, by combining synchrotron radiation and a double imaging electron/ion coincidence setup. The high-resolution threshold photoelectron spectra (TPES) of all three molecules are obtained experimentally from which the adiabatic ionization energies are reported with very high accuracy, particularly for 2-cyanonaphthalene, for which no data exist at this level of precision. Theoretical calculations are performed to compare with the TPES for the ground electronic state of the cations. Furthermore, the different features observed in the extended TPES have been assigned to the different molecular orbitals with the help of the outer valence Green's function calculations. The present experiments also shed light on the kinetic energy distribution of the photoelectrons as a function of the incident photon energy, to describe their contribution to the photoelectric heating effect in the interstellar medium. In this context, we show how kinetic energy distributions can be obtained from our data for any given photon energy, such as the omnipresent Ly α line, or any given interstellar radiation field (ISRF). In addition, from the total ion yields, we estimate the photorates for a few ISRFs. Finally, we discuss the photodissociation of the two cyanonaphthalenes, quoting the activation energies of the dissociation channels with the help of Rice–Ramsperger–Kassel–Marcus modeling. It is observed that CN substitution does not cause any appreciable change to the VUV dissociative photoionization relaxation channel. |
| first_indexed | 2024-03-07T19:22:18Z |
| format | Article |
| id | doaj.art-cdab9c297d514625ac46dc5b315a729e |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-07T19:22:18Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-cdab9c297d514625ac46dc5b315a729e2024-02-29T10:16:08ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-0196312910.3847/1538-4357/ad16d9Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas HeatingMadhusree Roy Chowdhury0https://orcid.org/0009-0004-5607-6781Gustavo A. Garcia1https://orcid.org/0000-0003-2915-2553Helgi R. Hrodmarsson2https://orcid.org/0000-0002-9613-5684Jean-Christophe Loison3https://orcid.org/0000-0001-8063-8685Laurent Nahon4https://orcid.org/0000-0001-9898-5693Synchrotron SOLEIL , L’Orme des Merisiers, Départementale 128, Saint Aubin F-91190, France ; madhusree.roy-chowdhury@synchrotron-soleil.frSynchrotron SOLEIL , L’Orme des Merisiers, Départementale 128, Saint Aubin F-91190, France ; madhusree.roy-chowdhury@synchrotron-soleil.frUniv Paris Est Creteil and Université Paris Cité , CNRS, LISA UMR 7583, 94010 Créteil, FranceUniversité Bordeaux , CNRS, Bordeaux INP, ISM, UMR 5255, Talence F-33400, FranceSynchrotron SOLEIL , L’Orme des Merisiers, Départementale 128, Saint Aubin F-91190, France ; madhusree.roy-chowdhury@synchrotron-soleil.frWe investigate the vacuum ultraviolet (VUV) photodynamics of gas phase 1- and 2-cyanonaphthalene and cyanobenzene, recently detected in the Taurus molecular cloud, by combining synchrotron radiation and a double imaging electron/ion coincidence setup. The high-resolution threshold photoelectron spectra (TPES) of all three molecules are obtained experimentally from which the adiabatic ionization energies are reported with very high accuracy, particularly for 2-cyanonaphthalene, for which no data exist at this level of precision. Theoretical calculations are performed to compare with the TPES for the ground electronic state of the cations. Furthermore, the different features observed in the extended TPES have been assigned to the different molecular orbitals with the help of the outer valence Green's function calculations. The present experiments also shed light on the kinetic energy distribution of the photoelectrons as a function of the incident photon energy, to describe their contribution to the photoelectric heating effect in the interstellar medium. In this context, we show how kinetic energy distributions can be obtained from our data for any given photon energy, such as the omnipresent Ly α line, or any given interstellar radiation field (ISRF). In addition, from the total ion yields, we estimate the photorates for a few ISRFs. Finally, we discuss the photodissociation of the two cyanonaphthalenes, quoting the activation energies of the dissociation channels with the help of Rice–Ramsperger–Kassel–Marcus modeling. It is observed that CN substitution does not cause any appreciable change to the VUV dissociative photoionization relaxation channel.https://doi.org/10.3847/1538-4357/ad16d9Interstellar mediumPhotoionizationPhotoelectron spectroscopy |
| spellingShingle | Madhusree Roy Chowdhury Gustavo A. Garcia Helgi R. Hrodmarsson Jean-Christophe Loison Laurent Nahon Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating The Astrophysical Journal Interstellar medium Photoionization Photoelectron spectroscopy |
| title | Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating |
| title_full | Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating |
| title_fullStr | Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating |
| title_full_unstemmed | Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating |
| title_short | Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating |
| title_sort | photoionization of nitrile substituted naphthalene and benzene cation spectroscopy photostability and implications for photoelectric gas heating |
| topic | Interstellar medium Photoionization Photoelectron spectroscopy |
| url | https://doi.org/10.3847/1538-4357/ad16d9 |
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