Disentangling UV photodesorption and photoconversion rates of H2O ice at 20 K: Measured with laser desorption post ionization mass spectrometry
Электронный научный архив УРФУ
Информация об архиве | Просмотр оригинала| Поле | Значение | |
| Заглавие |
Disentangling UV photodesorption and photoconversion rates of H2O ice at 20 K: Measured with laser desorption post ionization mass spectrometry
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| Автор |
Bulak, M.
Paardekooper, D. M. Fedoseev, G. Samarth, P. Linnartz, H. |
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| Тематика |
ASTROCHEMISTRY
ISM: MOLECULES METHODS: LABORATORY: SOLID STATE MOLECULAR PROCESSES PROTOPLANETARY DISKS ULTRAVIOLET: ISM COATINGS GASES ICE IONIZATION OF GASES IRRADIATION MASS SPECTROMETRY MOLECULES PHASE INTERFACES PHOTODISSOCIATION PHOTOIONIZATION PHOTOLYSIS PHOTONS SURFACE REACTIONS ASTROCHEMISTRY ISM:MOLECULES METHOD: LABORATORY: SOLID STATE METHODS:LABORATORY MOLECULAR PROCESS PHOTO-DESORPTION PHOTOCONVERSION PROTOPLANETARY DISKS ULTRAVIOLET: ISM UV PHOTONS DESORPTION |
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| Описание |
Context. The nondissociative ultraviolet photodesorption of water ice is a nonthermal desorption mechanism required to account for detected abundances of gas-phase water toward cold regions within the interstellar medium. Previous experimental and theoretical studies provide a range of photodesorption rates for H2O ice and point to a convoluted competition with other molecular processes following the absorption of a UV photon in the ice. Ultraviolet irradiation also induces photodissociation, resulting in the formation of radicals that may directly desorb triggering gas-phase reactions or recombine in surface reactions. Aims. In this work, we aim to quantify the effects of photodesorption and investigate photoconversion upon UV photolysis of an H2O ice. Methods. We irradiated a porous amorphous H2O ice at 20 K with UV photons in the 7-10.2 eV range and compared the measurements to a nearly identical experiment that included a layer of argon coating on top of the water ice. The purpose of the argon coating is to quench any type of photon-triggered desorption. To trace ice composition and thickness, laser desorption post ionization time-of-flight mass spectrometry was utilized. This method is independent of the (non)dissociative character of a process and provides a diagnostic tool different from earlier studies that allows an independent check. Results. The total photodesorption rate for a porous amorphous H2O ice at 20 K we derive is (1.0 ± 0.2) × 10-3 per incident UV photon (7-10.2 eV), which is in agreement with the available literature. This rate is based on the elemental balance of oxygen-bearing species. As a result, we placed an upper limit on the intact (H2O) and dissociative (OH) desorption rates equal to 1.0 × 10-3 per incident UV photon, while for the reactive desorption (O2), this limit is equal to 0.5 × 10-3 per incident UV photon. Photoconversion depletes the H2O ice at a rate of (2.3 ± 0.2) × 10-3 per incident UV photon. At low UV fluence (9.0 × 1017 photons cm-2), the loss of H2O is balanced by photoproduct formation (O2 and H2O2). At high UV fluence (4.5 × 1018 photons cm-2), about 50% of the initial H2O molecules are depleted. This amount is not matched by the registered O-bearing products, which points to an additional, unaccounted loss channel of H2O. © The Authors 2023.
H2020 Marie Skłodowska-Curie Actions, MSCA: 722346; European Commission, EC; Horizon 2020; Ministry of Science and Higher Education of the Russian Federation: FEUZ-2020-0038 M.B. and H.L. acknowledge the European Union (EU) and Horizon 2020 funding awarded under the Marie Skłodowska-Curie action to the EUROPAH consortium (grant number 722346) as well as NOVA 5 funding. Additional funding has been realized through a NWO-VICI grant. G.F. acknowledges financial support from the Russian Ministry of Science and Higher Education via the State Assignment Contract FEUZ-2020-0038. The authors acknowledge Andreas Riedo for initial experiments for this project and A.G.G.M. Tielens as well as M. Bertin for helpful discussions and feedback. |
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| Дата |
2024-04-05T16:33:07Z
2024-04-05T16:33:07Z 2023 |
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| Тип |
Article
Journal article (info:eu-repo/semantics/article) |info:eu-repo/semantics/publishedVersion |
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| Идентификатор |
Bulak, M, Paardekooper, D, Fedoseev, G, Samarth, P & Linnartz, H 2023, 'Disentangling UV photodesorption and photoconversion rates of H2O ice at 20 K: Measured with laser desorption post ionization mass spectrometry', Astronomy and Astrophysics, Том. 677, A99. https://doi.org/10.1051/0004-6361/202245273
Bulak, M., Paardekooper, D., Fedoseev, G., Samarth, P., & Linnartz, H. (2023). Disentangling UV photodesorption and photoconversion rates of H2O ice at 20 K: Measured with laser desorption post ionization mass spectrometry. Astronomy and Astrophysics, 677, [A99]. https://doi.org/10.1051/0004-6361/202245273 0004-6361 Final All Open Access, Hybrid Gold https://www.scopus.com/inward/record.uri?eid=2-s2.0-85172410960&doi=10.1051%2f0004-6361%2f202245273&partnerID=40&md5=81224430a8676a94a060b9b54ae98761 https://www.aanda.org/articles/aa/pdf/forth/aa45273-22.pdf http://elar.urfu.ru/handle/10995/130804 10.1051/0004-6361/202245273 85172410960 001067113700007 |
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| Язык |
en
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| Права |
Open access (info:eu-repo/semantics/openAccess)
cc-by https://creativecommons.org/licenses/by/4.0/ |
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| Формат |
application/pdf
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| Издатель |
EDP Sciences
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| Источник |
Astronomy & Astrophysics
Astronomy and Astrophysics |
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