Radical recombination in interstellar ices, a not so simple mechanism. Issue 4 (10th January 2017)

• Record Type: Journal Article
• Authors: Butscher, Teddy; Duvernay, Fabrice; Rimola, Albert; Segado-Centellas, Mireia; Chiavassa, Thierry
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 4(2017)
• Page Start: 2857
• Page End: 2866
• Publication Date: 2017-01-10
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp07024h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Formyl radical reactivity has been studied under astrophysical-like conditions, showing that its dimerization does not lead to glyoxal formation. It has also been shown that its reactivity could form glyceraldehyde and formaldehyde oligomers. Abstract : 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)CH2 OH) and ethylene glycol (HOCH2 CH2 OH) are formed by radical recombination between HC˙O and ˙CH2 OH, and by ˙CH2 OH dimerisation, respectively. Formyl (HC˙O), 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 HC˙O 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 HC˙O with another does not lead to the direct formation of glyoxal (HC(O)C(O)H) but yields H2 CO and CO. Results are also compared with those for the reaction between two ˙CH2 OH radicals and the recombination between HC˙O and ˙CH2 OH. 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.