Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact
Protonated hydrogen cyanide, HCNH<sup>+</sup>, is one of the most important molecules of interest in the astrophysical and astrochemical fields. This molecule not only plays the role of a reaction intermediary in various types of interstellar reactions but was also identified in Titan’s...
Saved in:
| Main Authors: | , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-12-01
|
| Series: | Atoms |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2218-2004/12/12/64 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850042336164184064 |
|---|---|
| author | Mehdi Adrien Ayouz Arnaud Buch |
| author_facet | Mehdi Adrien Ayouz Arnaud Buch |
| author_sort | Mehdi Adrien Ayouz |
| collection | DOAJ |
| description | Protonated hydrogen cyanide, HCNH<sup>+</sup>, is one of the most important molecules of interest in the astrophysical and astrochemical fields. This molecule not only plays the role of a reaction intermediary in various types of interstellar reactions but was also identified in Titan’s upper atmosphere. The cross sections for the dissociative recombination (DR) and vibrational (de-)excitation (VE and VDE) of HCNH<sup>+</sup> and its <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>CNH</mi><mn>2</mn><mo>+</mo></msubsup></semantics></math></inline-formula> isomer are computed using a theoretical approach based on a combination of the normal mode approximation for the vibrational states of the target ions and the UK R-matrix code to evaluate electron-ion scattering matrices for fixed geometries of ions. The theoretical convoluted DR cross section for HCNH<sup>+</sup> agrees well with the experimental data and a previous study. It was also found that the DR of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>CNH</mi><mn>2</mn><mo>+</mo></msubsup></semantics></math></inline-formula> isomer is important, which suggests that this ion might be present in DR experiments of HCNH<sup>+</sup>. Moreover, the ab initio calculations performed on the H<sub>2</sub>CN<sup>+</sup> isomer predict that this ion is a transition state. This result was confirmed by the study of the reaction path of the HCNH<sup>+</sup> isomerization that was carried out by evaluating the intrinsic reaction coordinate (IRC). Finally, thermally averaged rate coefficients derived from the cross sections are provided for temperatures in the 10–10,000 K range. A comprehensive set of calculations is performed to assess the uncertainty of the obtained data. These results should help in modeling non-LTE spectra of HCNH<sup>+</sup>, taking into account the role of its most stable isomer, in various astrophysical environments. |
| format | Article |
| id | doaj-art-e622ad643219478b901b313c8e94e5b7 |
| institution | DOAJ |
| issn | 2218-2004 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atoms |
| spelling | doaj-art-e622ad643219478b901b313c8e94e5b72025-08-20T02:55:35ZengMDPI AGAtoms2218-20042024-12-0112126410.3390/atoms12120064Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron ImpactMehdi Adrien Ayouz0Arnaud Buch1LGPM, CentraleSupélec, Université Paris-Saclay, 8-10 Rue Joliot-Curie, F-91190 Gif-sur-Yvette, FranceLGPM, CentraleSupélec, Université Paris-Saclay, 8-10 Rue Joliot-Curie, F-91190 Gif-sur-Yvette, FranceProtonated hydrogen cyanide, HCNH<sup>+</sup>, is one of the most important molecules of interest in the astrophysical and astrochemical fields. This molecule not only plays the role of a reaction intermediary in various types of interstellar reactions but was also identified in Titan’s upper atmosphere. The cross sections for the dissociative recombination (DR) and vibrational (de-)excitation (VE and VDE) of HCNH<sup>+</sup> and its <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>CNH</mi><mn>2</mn><mo>+</mo></msubsup></semantics></math></inline-formula> isomer are computed using a theoretical approach based on a combination of the normal mode approximation for the vibrational states of the target ions and the UK R-matrix code to evaluate electron-ion scattering matrices for fixed geometries of ions. The theoretical convoluted DR cross section for HCNH<sup>+</sup> agrees well with the experimental data and a previous study. It was also found that the DR of the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msubsup><mi>CNH</mi><mn>2</mn><mo>+</mo></msubsup></semantics></math></inline-formula> isomer is important, which suggests that this ion might be present in DR experiments of HCNH<sup>+</sup>. Moreover, the ab initio calculations performed on the H<sub>2</sub>CN<sup>+</sup> isomer predict that this ion is a transition state. This result was confirmed by the study of the reaction path of the HCNH<sup>+</sup> isomerization that was carried out by evaluating the intrinsic reaction coordinate (IRC). Finally, thermally averaged rate coefficients derived from the cross sections are provided for temperatures in the 10–10,000 K range. A comprehensive set of calculations is performed to assess the uncertainty of the obtained data. These results should help in modeling non-LTE spectra of HCNH<sup>+</sup>, taking into account the role of its most stable isomer, in various astrophysical environments.https://www.mdpi.com/2218-2004/12/12/64molecular cation reactive collisionsdissociative recombinationvibrational (de-)excitationR-matrix theoryinterstellar mediumTitan’s upper atmosphere |
| spellingShingle | Mehdi Adrien Ayouz Arnaud Buch Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact Atoms molecular cation reactive collisions dissociative recombination vibrational (de-)excitation R-matrix theory interstellar medium Titan’s upper atmosphere |
| title | Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact |
| title_full | Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact |
| title_fullStr | Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact |
| title_full_unstemmed | Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact |
| title_short | Theoretical Study of the Dissociative Recombination and Vibrational (De-)Excitation of HCNH<sup>+</sup> and Its Isomers by Electron Impact |
| title_sort | theoretical study of the dissociative recombination and vibrational de excitation of hcnh sup sup and its isomers by electron impact |
| topic | molecular cation reactive collisions dissociative recombination vibrational (de-)excitation R-matrix theory interstellar medium Titan’s upper atmosphere |
| url | https://www.mdpi.com/2218-2004/12/12/64 |
| work_keys_str_mv | AT mehdiadrienayouz theoreticalstudyofthedissociativerecombinationandvibrationaldeexcitationofhcnhsupsupanditsisomersbyelectronimpact AT arnaudbuch theoreticalstudyofthedissociativerecombinationandvibrationaldeexcitationofhcnhsupsupanditsisomersbyelectronimpact |