Open AccessAqueous depletion of Mg from olivine surfaces enhanced by ion irradiation
Author(s) -
Cantando E. D.,
Dukes C. A.,
Loeffler M. J.,
Baragiola R. A.
Publication year - 2008
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2008je003119
Subject(s) - irradiation , fluence , ion , olivine , x ray photoelectron spectroscopy , materials science , analytical chemistry (journal) , aqueous solution , magnesium , space weathering , surface layer , spectroscopy , mineralogy , chemistry , spectral line , layer (electronics) , nanotechnology , metallurgy , nuclear magnetic resonance , physics , environmental chemistry , organic chemistry , astronomy , quantum mechanics , nuclear physics
Laboratory experiments demonstrate that olivine irradiated with keV ions and exposed to water exhibits up to a 60% reduction from the original near‐surface concentration of magnesium, as measured by X‐ray photoelectron spectroscopy. The depth of this depletion layer is measured to be ∼15 nm. Irradiations were performed with 4 keV ions at fluences from 10 14 –10 19 ions cm –2 and water immersion times ranging from 3 s to more than 100 h in neutral (pH = 6.8), high‐purity water. The depletion of Mg depends strongly on ion fluence but weakly on immersion time after 3 min, when it saturates. Remarkably, ion irradiation enhances the rate of surface depletion of Mg from olivine by a factor of 26,000. This effect must be considered when assessing the surface composition of samples exposed to simulated space weathering in the laboratory and during the handling and analysis of irradiated extraterrestrial specimens acquired via sample return missions.