Oxygen on Ganymede: laboratory studies.

  title={Oxygen on Ganymede: laboratory studies.},
  author={Ricardo Alberto Vidal and David A. Bahr and Ra{\'u}l A. Baragiola and M Peters},
  volume={276 5320},
To test proposals for the origin of oxygen absorption bands in the visible reflectance spectrum of Ganymede, the reflectance of condensed films of pure oxygen (O2) and O2-water mixtures and the evolution of O2 from the films as a function of temperature were determined. Absorption band shapes and positions for oxygen at 26 kelvin were similar to those reported for Ganymede, whereas those for the mixtures were slightly shifted. The band intensity dropped by more than two orders of magnitude when… 
Laboratory studies of the optical properties and stability of oxygen on Ganymede
We present measurements of the optical properties of solid O2 and O2:H2O films and on the stability of oxygen in water ice at different temperatures. The experiments are meant to test hypotheses for
On the origin of molecular oxygen on the surface of Ganymede
The Geographic Distribution of Dense-phase O2 on Ganymede
Ground-based spectroscopy of Ganymede’s surface has revealed the surprising presence of dense-phase molecular oxygen (O2) via weak absorptions at visible wavelengths. To date, the state and stability
Ozone has been detected on the surface of Ganymede via observation of the Hartley band through the use of ultraviolet spectroscopy and is largely agreed upon to be formed by radiolytic processing via
Production of O2 on icy satellites by electronic excitation of low-temperature water ice
The large cross-section for O2 production suggests that electronic excitation plays an important part in the formation of O2 on Ganymede and Europa, rather than by diffusion and chemical recombination of precursor fragments as has been previously thought.
Photolysis of pure solid O3 and O2 films at 193 nm.
The general good agreement of the model with the data suggests the validity of the central assumption of efficient energy and spin relaxation of photofragments in the solid prior to their reactions with other species.
Laboratory studies on the formation of ozone (O3) on icy satellites and on interstellar and cometary ices
The formation of ozone (O3) in neat oxygen ices was investigated experimentally in a surface-scattering machine. At 11 K, solid oxygen was irradiated with energetic electrons; the chemical
Photochemistry of Ozone–Water Ices
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
Comment on “Laboratory studies of the optical properties and stability of oxygen on Ganymede” by Raul A. Baragiola and David A. Bahr
It has been over 15 years since Brown et al. [1982] showed that the bombardment of the icy satellites by magnetospheric plasma particles would produce significant quantities of O2, including an O2
Decomposition of solid amorphous hydrogen peroxide by ion irradiation.
From the measurements, radiation yields are derived, which are found to be particularly high for the decomposition of hydrogen peroxide; this can be explained by the occurrence of a chemical chain reaction.


O2 on Ganymede: Spectral characteristics and plasma formation mechanisms
Weak absorption features in the visible reflectance spectrum of Jupiter's satellite Ganymede have been correlated to those observed in the spectrum of molecular oxygen. We examine the spectral
Detection of Ozone on Ganymede
An absorption band at 260 nanometers on the trailing hemisphere of Ganymede, identified as the Hartley band of ozone (O3), was measured with the Hubble Space Telescope, and apparently this O2-O3 “atmosphere” is trapped in GanyMede's surface ice, an inference consistent with the shift and broadening of the band.
Charge‐coupled device spectra of the Galilean satellites: Molecular oxygen on Ganymede
We have obtained 3200–7800 A CCD spectra of the Galilean satellites at a variety of orbital longitudes, with spectral resolution between 3 and 18 A and signal-to-noise ratios of up to 2000 at 6000 A.
Stability of an oxygen atmosphere on ganymede
Alteration of the UV-visible reflectance spectra of H2O ice by ion bombardment
Abstrac%. Satellites in the Jovian and temperature was measured by a cryodiode; the Saturnian system exhibit differences in measurement proved to be accurate to about 1 K by reflectivity between
Absorption measurements of oxygen between 330 and 1140 nm
The absorption spectrum of O2 and O2-O2 collision pairs were measured over the wavelength range from 330 to 1140 nm using pressures of O2 from 1 to 55 atm at 298 K. Absorption cross sections,
Sublimation of vapor-deposited water ice below 170 K, and its dependence on growth conditions.
It is found that fresh films have an enhanced sublimation rate, which decays in time and which depends on film thickness and growth temperatures, and this is attributed to sublimating from regions containing amorphous ice, which transforms with time into the less volatile crystalline ice.
Astrophysical implications of amorphous ice—a microporous solid
Since the observation of the 3-µm band in interstellar infrared sources1–3, vapour-deposited amorphous ice, H2O(as), has been discussed as a major component of comets4–9, of satellites of the outer
Structural transitions in amorphous water ice and astrophysical implications.
The structural transition from Iah to Ial is responsible for the diffusion and recombination of radicals in ultraviolet-photolyzed interstellar ices at low temperatures and can be used to explain hitherto anomalous properties of astrophysical ices.