Počet záznamů: 1
Ionization of Ammonia Nanoices with Adsorbed Methanol Molecules
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SYSNO ASEP 0495950 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Ionization of Ammonia Nanoices with Adsorbed Methanol Molecules Tvůrce(i) Fárník, Michal (UFCH-W) RID, ORCID
Pysanenko, Andriy (UFCH-W) RID, ORCID
Moriová, Kamila (UFCH-W)
Ballauf, L. (AT)
Scheier, P. (AT)
Chalabala, J. (CZ)
Slavíček, Petr (UFCH-W) RIDZdroj.dok. Journal of Physical Chemistry A. - : American Chemical Society - ISSN 1089-5639
Roč. 122, č. 43 (2018), s. 8458-8468Poč.str. 11 s. Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova PROTON-TRANSFER REACTIONS ; HYDROGEN-BONDED CLUSTERS ; INTERSTELLAR ICE ANALOGS Vědní obor RIV CF - Fyzikální chemie a teoretická chemie Obor OECD Physical chemistry CEP GA17-04068S GA ČR - Grantová agentura ČR Institucionální podpora UFCH-W - RVO:61388955 UT WOS 000449308300004 EID SCOPUS 85055819539 DOI 10.1021/acs.jpca.8b07974 Anotace Large ammonia clusters represent a model system of ices that are omnipresent throughout the space. The interaction of ammonia ices with other hydrogen-boding molecules such as methanol or water and their behavior upon an ionization are thus relevant in the astrochemical context. In this study, ammonia clusters (NH3)N with the mean size N̅ ≈ 230 were prepared in molecular beams and passed through a pickup cell in which methanol molecules were adsorbed. At the highest exploited pickup pressures, the average composition of (NH3)N(CH3OH)M clusters was estimated to be N:M ≈ 210:10. On the other hand, the electron ionization of these clusters yielded about 75% of methanol-containing fragments (NH3)n(CH3OH)mH+ compared to 25% contribution of pure ammonia (NH3)nH+ ions. On the basis of this substantial disproportion, we propose the following ionization mechanism: The prevailing ammonia is ionized in most cases, resulting in NH4+ core solvated most likely with four ammonia molecules, yielding the well-known “magic number” structure (NH3)4NH4+. The methanol molecules exhibit a strong propensity for sticking to the fragment ion. We have also considered mechanisms of intracluster reactions. In most cases, proton transfer between ammonia units take place. The theoretical calculations suggested the proton transfer either from the methyl group or from the hydroxyl group of the ionized methanol molecule to ammonia to be the energetically open channels. However, the experiments with selectively deuterated methanols did not show any evidence for the D+ transfer from the CD3 group. The proton transfer from the hydroxyl group could not be excluded entirely or confirmed unambiguously by the experiment. Pracoviště Ústav fyzikální chemie J.Heyrovského Kontakt Michaela Knapová, michaela.knapova@jh-inst.cas.cz, Tel.: 266 053 196 Rok sběru 2019
Počet záznamů: 1