Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds

Sulfur-bearing molecules are key constituents of the interstellar medium (ISM). Particularly, hydrogen sulfide (H2S) and cyano (CN) radicals are key precursors of prebiotic molecules in the ISM. However, the ultralow-temperature gas-phase reactivity remains poorly characterized yet. We report the fi...

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Autores: Martínez , Francisco, González Pérez de Madrid, Daniel, Lema Saavedra, Anxo, Martinez Nuñez, Emilio, Fernández Ramos, Antonio, Agundez , Marcelino, Cernicharo , José, Antiñolo Navas, María, Jiménez Martínez, Elena
Tipo de recurso: artículo
Fecha de publicación:2026
País:España
Institución:Consejo Superior de Investigaciones Científicas (CSIC)
Repositorio:RUIdeRA. Repositorio Institucional de la UCLM
OAI Identifier:oai:ruidera.uclm.es:10578/47791
Acceso en línea:https://doi.org/10.3847/1538-4357/ae421d
https://hdl.handle.net/10578/47791
Access Level:acceso abierto
Palabra clave:Cold molecular clouds
Interstellar medium (ISM)
Prebiotic molecules
Sulfur astrochemistry
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spelling Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular CloudsMartínez , FranciscoGonzález Pérez de Madrid, DanielLema Saavedra, AnxoMartinez Nuñez, EmilioFernández Ramos, AntonioAgundez , MarcelinoCernicharo , JoséAntiñolo Navas, MaríaJiménez Martínez, ElenaCold molecular cloudsInterstellar medium (ISM)Prebiotic moleculesSulfur astrochemistrySulfur-bearing molecules are key constituents of the interstellar medium (ISM). Particularly, hydrogen sulfide (H2S) and cyano (CN) radicals are key precursors of prebiotic molecules in the ISM. However, the ultralow-temperature gas-phase reactivity remains poorly characterized yet. We report the first experimental and theoretical investigation of the CN + H2S reaction under conditions relevant to cold molecular clouds. Rate coefficients were determined between 11.7 and 45.5 K using the Cinétique de Réaction en Ecoulement Supersonique Uniforme technique coupled with pulsed laser photolysis–laser-induced fluorescence, yielding negligible temperature dependence values around 4.0 × 10-10 cm3 s-1 in excellent agreement with complementary rate coefficients calculations. AutoMeKin and coupled-cluster theory reveal that the dominant channel involves CN addition to H2S, followed by H elimination, forming HSCN. This pathway is energetically more favorable than the previously assumed HCN + SH channel and exhibits submerged transition states, suggesting efficient reactivity at ultracold temperatures. Astrochemical modeling indicates that inclusion of this reaction in chemical networks enhances HSCN abundances in dark clouds, with contributions comparable to those from dissociative recombination routes. Although the CN + H2S reaction is absent from current astrochemical databases, our results demonstrate its potential role in sulfur–nitrogen coupling and the formation of prebiotic molecules in the ISM. These findings underscore the need to update chemical models to account for this process and improve predictions of sulfur chemistry in star-forming regions.American Astronomical Society IOP Publishing202620262026info:eu-repo/semantics/articleapplication/pdfapplication/pdfhttps://doi.org/10.3847/1538-4357/ae421dhttps://hdl.handle.net/10578/47791reponame:RUIdeRA. Repositorio Institucional de la UCLMinstname:Consejo Superior de Investigaciones Científicas (CSIC)InglésPID2020-113936GB-I00SBPLY/23/180225/0000542022-GRIN-34143ED431C 2025/06info:eu-repo/semantics/openAccessoai:ruidera.uclm.es:10578/477912026-05-27T07:36:41Z
dc.title.none.fl_str_mv Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
title Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
spellingShingle Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
Martínez , Francisco
Cold molecular clouds
Interstellar medium (ISM)
Prebiotic molecules
Sulfur astrochemistry
title_short Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
title_full Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
title_fullStr Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
title_full_unstemmed Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
title_sort Revealing that the Gas-phase Reaction of CN with H2S Can Be a Source of HSCN in Interstellar Molecular Clouds
dc.creator.none.fl_str_mv Martínez , Francisco
González Pérez de Madrid, Daniel
Lema Saavedra, Anxo
Martinez Nuñez, Emilio
Fernández Ramos, Antonio
Agundez , Marcelino
Cernicharo , José
Antiñolo Navas, María
Jiménez Martínez, Elena
author Martínez , Francisco
author_facet Martínez , Francisco
González Pérez de Madrid, Daniel
Lema Saavedra, Anxo
Martinez Nuñez, Emilio
Fernández Ramos, Antonio
Agundez , Marcelino
Cernicharo , José
Antiñolo Navas, María
Jiménez Martínez, Elena
author_role author
author2 González Pérez de Madrid, Daniel
Lema Saavedra, Anxo
Martinez Nuñez, Emilio
Fernández Ramos, Antonio
Agundez , Marcelino
Cernicharo , José
Antiñolo Navas, María
Jiménez Martínez, Elena
author2_role author
author
author
author
author
author
author
author
dc.subject.none.fl_str_mv Cold molecular clouds
Interstellar medium (ISM)
Prebiotic molecules
Sulfur astrochemistry
topic Cold molecular clouds
Interstellar medium (ISM)
Prebiotic molecules
Sulfur astrochemistry
description Sulfur-bearing molecules are key constituents of the interstellar medium (ISM). Particularly, hydrogen sulfide (H2S) and cyano (CN) radicals are key precursors of prebiotic molecules in the ISM. However, the ultralow-temperature gas-phase reactivity remains poorly characterized yet. We report the first experimental and theoretical investigation of the CN + H2S reaction under conditions relevant to cold molecular clouds. Rate coefficients were determined between 11.7 and 45.5 K using the Cinétique de Réaction en Ecoulement Supersonique Uniforme technique coupled with pulsed laser photolysis–laser-induced fluorescence, yielding negligible temperature dependence values around 4.0 × 10-10 cm3 s-1 in excellent agreement with complementary rate coefficients calculations. AutoMeKin and coupled-cluster theory reveal that the dominant channel involves CN addition to H2S, followed by H elimination, forming HSCN. This pathway is energetically more favorable than the previously assumed HCN + SH channel and exhibits submerged transition states, suggesting efficient reactivity at ultracold temperatures. Astrochemical modeling indicates that inclusion of this reaction in chemical networks enhances HSCN abundances in dark clouds, with contributions comparable to those from dissociative recombination routes. Although the CN + H2S reaction is absent from current astrochemical databases, our results demonstrate its potential role in sulfur–nitrogen coupling and the formation of prebiotic molecules in the ISM. These findings underscore the need to update chemical models to account for this process and improve predictions of sulfur chemistry in star-forming regions.
publishDate 2026
dc.date.none.fl_str_mv 2026
2026
2026
dc.type.none.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://doi.org/10.3847/1538-4357/ae421d
https://hdl.handle.net/10578/47791
url https://doi.org/10.3847/1538-4357/ae421d
https://hdl.handle.net/10578/47791
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv PID2020-113936GB-I00
SBPLY/23/180225/000054
2022-GRIN-34143
ED431C 2025/06
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv American Astronomical Society IOP Publishing
publisher.none.fl_str_mv American Astronomical Society IOP Publishing
dc.source.none.fl_str_mv reponame:RUIdeRA. Repositorio Institucional de la UCLM
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str RUIdeRA. Repositorio Institucional de la UCLM
collection RUIdeRA. Repositorio Institucional de la UCLM
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,81155

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