ALTERATION OF THE UVVISIBLE 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 their "leading" and external calibration. With an electric heater in "trailing" surfaces which can affect the local the copper block, the cooled target could be vapor pressure. Since these differences are warmed up to above 100 K. The water films were thought to be due to differences in the flux of grown on a thin substrate covering the copper bombarding magnetospheric ions, we studied the block that contained an alpha particle source. influence of ion impact on the UV-visible The measurement of the energy loss of the very reflectance of water ice surfaces (20-90 K) by low flux of alpha particles as they pass through keV ion bombardment. An observed decrease in the film gave a thickness through the use of reflectance in the UV is attributed to tabulated stopping powers. The growing rate was rearrangement processes that affect the physical 1 •m/min using a gas manifold filled with water microstructure and surface "roughness." The vapor from HPLC-H20 (organic free; residue after ratio in reflectance of bombarded to freshly evaporation: 0.9 ppm). Fihns were grown using a deposited films is compared to the ratio of the nozzle ~3 cm from the target and using a reflectance of the leading and trailing capillary array plate ~5 mm from the target. The hemispheres for Europa and Ganymede. dispersion in energies of alpha particles from the source below the film shows that the film