Radical recombination in interstellar ices, a not so simple mechanism

Teddy Butscher, Fabrice Duvernay, Albert Rimola, Mireia Segado-Centellas, Thierry Chiavassa

Research output: Contribution to journalArticleResearchpeer-review

24 Citations (Scopus)

Abstract

© 2017 the Owner Societies. Many complex organic molecules (hereafter COMs) have been detected in different regions of the interstellar medium (ISM). In each region, different energetic processes-UV irradiation, atom bombardments, etc.-that could be linked to the formation of detected COMs may occur depending on the environment. Several formation mechanisms were proposed but increasing attention is paid to radical recombination reactions. Previous studies showed that glycolaldehyde (HC(O)CH2OH) and ethylene glycol (HOCH2CH2OH) are formed by radical recombination between HCO and CH2OH, and by CH2OH dimerisation, respectively. Formyl (HCO), one of the most famous astrophysically-relevant radical species, has been detected as a gaseous component of the ISM. Its reactivity was already attributed to the formation of several COMs. This work aims to study the dimerisation of formyl radical HCO using a cryogenic matrix technique. The evolution of the chemical sample composition is monitored by infrared spectroscopy and by mass spectrometry during temperature programmed desorption (TPD) monitoring. Results indicate that the reaction of one HCO with another does not lead to the direct formation of glyoxal (HC(O)C(O)H) but yields H2CO and CO. Results are also compared with those for the reaction between two CH2OH radicals and the recombination between HCO and CH2OH. Also, glyceraldehyde was tentatively detected in our experiment using different spectroscopic techniques. A radical mechanism is proposed to explain its formation in our experiments. Complementary quantum chemical calculations provide an atomistic interpretation of the experimental findings.
Original languageEnglish
Pages (from-to)2857-2866
JournalPhysical Chemistry Chemical Physics
Volume19
Issue number4
DOIs
Publication statusPublished - 1 Jan 2017

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