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http://hdl.handle.net/20.500.12386/27848
Title: | X-Ray Photo-desorption of H2O:CO:NH3Circumstellar Ice Analogs: Gas-phase Enrichment | Authors: | JIMENEZ ESCOBAR, Antonio CIARAVELLA, Angela CECCHI PESTELLINI, Cesare Huang, C.-H. Sie, N.-E. Chen, Y.-J. Muñoz Caro, G. M. |
Issue Date: | 2018 | Journal: | THE ASTROPHYSICAL JOURNAL | Number: | 868 | Issue: | 1 | First Page: | 73 | Abstract: | We study the photo-desorption occurring in H2O:CO:NH3 ice mixtures irradiated with monochromatic (550 and 900 eV) and broadband (250-1250 eV) soft X-rays generated at the National Synchrotron Radiation Research Center (Hsinchu, Taiwan). We detect many masses photo-desorbing, from atomic hydrogen (m/z = 1) to complex species with m/z = 69 (e.g., C3H3NO, C4H5O, C4H7N), supporting the enrichment of the gas phase. At low numbers of absorbed photons, substrate-mediated, exciton-promoted desorption dominates the photo-desorption yield, inducing the release of weakly bound (to the surface of the ice) species; as the number of weakly bound species declines, the photo-desorption yield decreases about one order of magnitude, until porosity effects, reducing the surface/volume ratio, produce a further drop of the yield. We derive an upper limit to the CO photo-desorption yield, which in our experiments varies from 1.4 to 0.007 molecules photon-1 in the range 10^15-10^20 absorbed photons cm-2. We apply these findings to a protoplanetary disk model irradiated by a central T Tauri star. | URI: | http://hdl.handle.net/20.500.12386/27848 | URL: | https://iopscience.iop.org/article/10.3847/1538-4357/aae711 | ISSN: | 0004-637X | DOI: | 10.3847/1538-4357/aae711 | Bibcode ADS: | 2018ApJ...868...73J | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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Jim%C3%A9nez-Escobar_2018_ApJ_868_73.pdf | Pdf editoriale | 963.65 kB | Adobe PDF | View/Open |
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