Issue |
A&A
Volume 682, February 2024
|
|
---|---|---|
Article Number | A158 | |
Number of page(s) | 11 | |
Section | Atomic, molecular, and nuclear data | |
DOI | https://doi.org/10.1051/0004-6361/202347889 | |
Published online | 16 February 2024 |
Indene energetic processing in ice mantles in the interstellar medium
1
Instituto de Estructura de la Materia, IEM-CSIC,
Calle Serrano 121,
28006
Madrid,
Spain
e-mail: belen.mate@csic.es
2
Instituto de Física Fundamental, IFF-CSIC,
Calle Serrano 123,
28006
Madrid,
Spain
Received:
6
September
2023
Accepted:
6
December
2023
Context. Indene, a small PAH, has been detected in the gas phase in the cold dense cloud TMC-1. Due to the low temperature in the cloud, below indene condensation temperature, its presence in the ice mantles of dust grains is likely.
Aims. The aim of this work is to study the stability of indene against the energetic processing by VUV photons or cosmic rays in the ice mantles of dense molecular clouds.
Methods. Ice layers of pure indene or indene diluted in water ice were grown by vapor deposition on a cold surface held at 10 K, 100 K, or 140 K. The samples were processed with VUV photons (120–180 nm) and 5 keV electrons and the destruction of indene was monitored by following the decay of its absorption bands in the infrared (IR) spectrum. Finally, we recorded the mass spectra of the decomposition products sublimated by thermal programmed desorption of the processed samples.
Results. Photolysis and radiolysis cross-sections, along with half-life energy doses for indene in the solid form and diluted in water ice matrices at 10 K were derived. Ketones and alcohols were identified as the main processing products in indene and water–ice mixtures
Conclusions. Dilution in water ice enhances the destruction rate of indene under energetic processing. The molecule is expected to survive for more than 107 yr in the ice mantles of grains in the interior of dense clouds, but it will end up getting destroyed within the next few hundred years by the intense VUV field in the diffuse region at the edges of the cloud.
Key words: astrochemistry / molecular data / molecular processes / methods: laboratory: molecular / ISM: molecules / infrared: ISM
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This article is published in open access under the Subscribe to Open model. Subscribe to A&A to support open access publication.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.