The presence of NH2OH, one of the main precursors in the formation of amino-acids, on dust grain mantles, may be the most obvious elucidation for the creation of large prebiotic molecules in the interstellar medium. However, while many laboratory experimental studies, to simulate the icy grain chemistry in space, found that NH2OH molecules may be easily formed in solid phase with high abundances and then they should desorb, through a temperature induced desorption into the gas phase, with the same high abundances; all the spatial observations conclude that NH2OH is not detected in gas phase within any of the explored astronomical sources. Such inconsistencies between laboratory experiment simulations and spatial observations lead our investigations towards the characterization of some thermal induced reactions at cryogenic temperatures that may occur in solid phase on the icy interstellar grains, leading to the dissociation of some stable chemical species, even before reaching their desorption temperatures. Those dissociative thermal processes may involve only stable molecules such as NH2OH + H2O reactions or radical species such as NH2OH + OH or NH3 + N(4S). We show through these studies that several chemical transformations (Hydrogen abstraction, fragmentation, isomerization...) previously thought to occur exclusively via UV photon or energetic particle irradiations may take place, in solid phase just by stimulating an increase of the temperature in a range of 3-100K.

Thermally induced low temperature fragmentation reaction in solid phase: Possible answers to the non-detection of some interstellar chemical species

253rd National Meeting (2017)

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