When a salt like NaCl is dissolved in water, sodium and chlorine separate in ionic form Na+
, become surrounded by water molecules and disperse. This deeply modifies the nature of the solvent which becomes for example, a good electricity conductor. At the surface, the distribution of the ions remains however poorly known, although many "contact" properties depend on it.
By studying mixtures of salt solutions by x-ray fluorescence under grazing incidence at ESRF (synchrotron of Grenoble), it was possible to precisely determine their composition at the surface. More...