Missing sulfur in allotropes

Sulfur is depleted in dense clouds by a factor of 100. It is speculated that sulfur is stored in UV-photoprocessed icy grains. For this bachelor research project, photochemistry of H2S ice analogues in the lab was thoroughly studied. We grew pure H2S ice samples and analyzed the UV irradiation kinetics as well as the resulting photoproducts using the CRYOPAD2 and MATRI2CES setups at the Laboratory for Astrophysics at Leiden University. Irradiation and Temperature Programmed Desorption (TPD) experiments were performed on CRYOPAD2 yielding desorption temperatures for the first four hydrogenated sulfur chains (H2Sx, x up to 4) and a photochemical desorption rate of 10−3 photons cm−2. No evidence for the formation of pure sulfur allotropes was found. The MATRI2CES setup, which is uniquely configured for laser ablated spectroscopy, allowed measurements of refractory photoproducts. The total sulfur budged in an irradiated H2S ice has been found to be a factor 2.9 higher than the leftover...Show moreSulfur is depleted in dense clouds by a factor of 100. It is speculated that sulfur is stored in UV-photoprocessed icy grains. For this bachelor research project, photochemistry of H2S ice analogues in the lab was thoroughly studied. We grew pure H2S ice samples and analyzed the UV irradiation kinetics as well as the resulting photoproducts using the CRYOPAD2 and MATRI2CES setups at the Laboratory for Astrophysics at Leiden University. Irradiation and Temperature Programmed Desorption (TPD) experiments were performed on CRYOPAD2 yielding desorption temperatures for the first four hydrogenated sulfur chains (H2Sx, x up to 4) and a photochemical desorption rate of 10−3 photons cm−2. No evidence for the formation of pure sulfur allotropes was found. The MATRI2CES setup, which is uniquely configured for laser ablated spectroscopy, allowed measurements of refractory photoproducts. The total sulfur budged in an irradiated H2S ice has been found to be a factor 2.9 higher than the leftover unprocessed H2SShow less

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Missing sulfur in allotropes