Lunar and Planetary Laboratory
University of Arizona, Tucson, AZ 85721
(JGR 97, E11, 18,257-18,264, Nov.25, 1992)
An explanation is given for time-variable and spatially discrete
enhancements of neutral sodium (Na) and potassium (K) in Mercury's
atmosphere. Some locations of increase intensity can be explained in
terms of sodium and potassium ion implantation into the surface
regolith grains during the long, 88 Earth day, Mercurian night with
subsequent diffusion to the atmosphere when the enriched surface of
Mercury rotates into the intense sunlight of day. Support for the
suggested mehcanism is shown by the K data which show a marked
moring/afternoon assymmetry and can be explained by time and
temperature dependent degassing. The magnetospheric mechanism necessary
for ion implantation is discussed as is the diffusion mechanism.
Alternative source, recycling, and distribution processes are also
Correction in JGR 98, E1, p.1231, Jan.25, 1993.