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Ices are widely present in the cold regions across the Universe, for instance, in the interstellar medium as mantles on interstellar and circumstellar dust and on the surfaces of small bodies of the Solar System - beyond the distance around 3-5 AU known as the “snowline" (i.e. at temperatures below 150-170 K). The continuous energetic processing of icy objects in the Solar System induces physical and chemical changes within the ice. Laboratory experiments that simulate energetic processing (ions, photons, and electrons) of ices are therefore essential for interpreting and directing future astronomical observations. Here we provide vacuum ultraviolet (VUV) and UV-Vis photoabsorption spectroscopic data of pristine and energetically processed (electron irradiated) space-related ices. Experiments were performed using a custom-made Portable Astrochemistry Chamber (PAC), which has a base pressure of 10-9 mbar. Photoabsorption spectra of ices were measured at the AU-UV beam line of the ASTRID2 synchrotron light source at Aarhus University in Denmark (see Eden et al. 2006; Palmer et al. 2015). We present the results of three series of experiments: one dedicated to the study of nitrogen- and oxygen-rich ices (Ioppolo et al., 2020); the other one to the spectroscopic study of carbonic acid as formed and destroyed under conditions relevant to space (Ioppolo et al., 2021); and the third one to the study of photoabsorption spectra of O2 ice, both pure and mixed with other species (Migliorini et al, 2021). Results are discussed in light of their relevance to various astrophysical environments, e.g., the icy moons of Saturn and Jupiter. Laboratory VUV-UV-vis spectra of ices can help their future identification on the surface of icy objects in the Solar System by the upcoming Jupiter ICy moons Explorer mission and on interstellar dust by the James Webb Space Telescope spacecraft. This research was partly supported by the Italian Space Agency (Grant ASI-INAF n. 2018-25-HH-0). REFERENCES: Eden, S., Limão-Vieira, P., Hoffmann, S. V., & Mason, N. J. 2006, Chem. Phys., 323, 313 Ioppolo, S., Kanuchova Z., James, R.L., Dawes, A., Jones, N.C., Hoffmann, S.V., Mason, N.J., Strazzulla, G. 2020, Astron. Astrophys. 641, A154 Ioppolo, S., Kanuchova Z., James, R.L., Dawes, A., Ryabov, A., Dezalay, J., Jones, N.C., Hoffmann, S.V., Mason, N.J., Strazzulla, G. 2021, Astron. Astrophys. 645, A172 Migliorini, A., Kanuchova Z., Ioppolo, S., Jones, N.C., Hoffmann, S.V., Tosi, F., Piccioni, G., Barbieri, M. 2021, Icarus, submitted Palmer, M. H., Ridley, T., Hoffmann, S. V., et al. 2015, J. Chem. Phys., 142, 134302 |
