As diffractive element a TAP crystal (2d: 25.757 Å) was used for the detection of the KL3 radiation of F (677eV), Na (1040eV), and Al (1486eV), and a PET crystal (2d: 8.742 Å) for P (2010 eV) and S (2309 eV). All lines were recorded over a time of 60 s (peak) and 2 x 30 s (background), respectively. These times were chosen to guarantee sample stability under the electron beam; for observation times of 120 s, we started to see dynamic variations in the Na ion concentration.