Chen, Y. -J.Y. -J.ChenJuang, K. -J.K. -J.JuangNuevo, M.M.NuevoJIMENEZ ESCOBAR, AntonioAntonioJIMENEZ ESCOBARMuñoz Caro, G. M.G. M.Muñoz CaroQiu, J. -M.J. -M.QiuChu, C. -C.C. -C.ChuYih, T. -S.T. -S.YihWu, C. -Y. R.C. -Y. R.WuFung, H. -S.H. -S.FungIp, W. -H.W. -H.Ip2020-03-192020-03-1920150004-637Xhttp://hdl.handle.net/20.500.12386/23410Carbonyl sulfide (OCS) is a key molecule in astrobiology that acts as a catalyst in peptide synthesis by coupling amino acids. Experimental studies suggest that hydrogen sulfide (H<SUB>2</SUB>S), a precursor of OCS, could be present in astrophysical environments. In the present study, we used a microwave-discharge hydrogen-flow lamp, simulating the interstellar UV field, and a monochromatic synchrotron light beam to irradiate CO:H<SUB>2</SUB>S and CO<SUB>2</SUB>:H<SUB>2</SUB>S ice mixtures at 14 K with vacuum ultraviolet (VUV) or extreme ultraviolet (EUV) photons in order to study the effect of the photon energy and carbon source on the formation mechanisms and production yields of S-containing products (CS<SUB>2</SUB>, OCS, SO<SUB>2</SUB>, etc.). Results show that (1) the photo-induced OCS production efficiency in CO:H<SUB>2</SUB>S ice mixtures is higher than that of CO<SUB>2</SUB>:H<SUB>2</SUB>S ice mixtures; (2) a lower concentration of H<SUB>2</SUB>S enhances the production efficiency of OCS in both ice mixtures; and (3) the formation pathways of CS<SUB>2</SUB> differ significantly upon VUV and EUV irradiations. Furthermore, CS<SUB>2</SUB> was produced only after VUV photoprocessing of CO:H<SUB>2</SUB>S ices, while the VUV-induced production of SO<SUB>2</SUB> occurred only in CO<SUB>2</SUB>:H<SUB>2</SUB>S ice mixtures. More generally, the production yields of OCS, H<SUB>2</SUB>S<SUB>2</SUB>, and CS<SUB>2</SUB> were studied as a function of the irradiation photon energy. Heavy S-bearing compounds were also observed using mass spectrometry during the warm-up of VUV/EUV-irradiated CO:H<SUB>2</SUB>S ice mixtures. The presence of S-polymers in dust grains may account for the missing sulfur in dense clouds and circumstellar environments.ELETTRONICOenArticle10.1088/0004-637X/798/2/802-s2.0-84924265613000350853700015https://iopscience.iop.org/article/10.1088/0004-637X/798/2/802015ApJ...798...80CFIS/05 - ASTRONOMIA E ASTROFISICA