0000000000424029
AUTHOR
A. Jiménez-escobar
SOFT X-RAY IRRADIATION OF PURE CARBON MONOXIDE INTERSTELLAR ICE ANALOGUES
There is an increasing evidence for the existence of large organic molecules in the interstellar and circumstellar medium. Very few among such species are readily formed in conventional gas-phase chemistry under typical conditions of interstellar clouds. Attention has therefore focused on interstellar ices as a potential source of these relatively complex species. Laboratory experiments show that irradiation of interstellar ice analogues by fast particles or ultraviolet radiation can induce significant chemical complexity. However, stars are sources of intense X-rays at almost every stage of their formation and evolution. Such radiation may thus provide chemical changes in regions where ult…
Synthesis of complex organic molecules in soft x-ray irradiated ices
We study the chemical evolution of H2O:CO:NH3 ice mixtures irradiated with soft X-rays, in the range 250-1250 eV. We identify many nitrogen-bearing molecules such as e.g., OCN-, NH4+ , HNCO, CH3CN, HCONH2, and NH2COCONH2. Several infrared features are compatible with glycine or its isomers. During the irradiation, we detected through mass spectroscopy many species desorbing the ice. Such findings support either the infrared identifications and reveal less abundant species with not clear infrared features. Among them, m/z = 57 has been ascribed to methyl isocyanate (CH3NCO), a molecule of prebiotic relevance, recently detected in protostellar environments. During the warm up after the irradi…
X-ray versus Ultraviolet Irradiation of Astrophysical Ice Analogs Leading to Formation of Complex Organic Molecules
In astrochemistry, complex organic molecules (COMs) are defined as species with at least one C atom and six or more atoms in total. More than 70 COMs were detected toward various interstellar and c...
Chemical Evolution of Interstellar Methanol Ice Analogs upon Ultraviolet Irradiation: The Role of the Substrate
An important issue in the chemistry of interstellar ices is the role of dust materials. In this work, we study the effect of an amorphous water-rich magnesium silicate deposited onto ZnSe windows on the chemical evolution of ultraviolet-irradiated methanol ices. For comparison, we also irradiate similar ices deposited onto bare ZnSe windows. Silicates are produced at relatively low temperatures exploiting a sol-gel technique. The chemical composition of the synthesized material reflects the forsterite stoichiometry. Si-OH groups and magnesium carbonates are incorporated during the process. The results show that the substrate material does affect the chemical evolution of the ice. In particu…