["Johnson, Paul V","Markus, Charles R","Hodyss, Robert"]2019-11-01期刊论文
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Ozone is known to be present within the surface ice of Jupiter's moon Ganymede as well as Saturn's moons Dione and Rhea. Given the ubiquity of solar photons incident on these water-ice-dominated surfaces, experiments were conducted to better understand the photochemistry of ozone-water ice mixtures. Samples were deposited as thin films in a vacuum chamber under temperature and pressure conditions relevant to satellites in the outer solar system. Chemical changes in the ices were monitored with infrared spectroscopy as they were exposed to ultraviolet light at 116.5/123.6, 147, and 254 nm emitted from Kr, Xe, and Hg resonant lamps, respectively. In all instances, hydrogen peroxide formed after ultraviolet irradiation, while the amount of ozone present decreased. Of the wavelengths tested, irradiation at 254 rim induced the most rapid change both in terms of irradiation time and number of incident photons. This work emphasizes the importance of wavelengths longer than the vacuum ultraviolet in the chemical evolution of ozone on Ganymede, Dione, and Rhea.
