# Synchrotron X-ray Microprobes: An Application on Ancient Ceramics
## 3 Results
### SR Based X-ray Methods Using Microprobes
#### 3.2.2 \(\upmu\)XANES Spectra and Maps  
XANES Fe K-edge spectra acquired on the black gloss layer--with the sample cross-section facing the incoming beam--show the presence of both Fe\({}^{2+}\) and Fe\({}^{3+}\) phases, as already found in some of these glosses analysed in our previous work [22]. As it can be seen in Figure 2, spectra collected on Laconian and Chalcidian samples exhibit in some cases (GEL2, GEL3, GEL5, GEVN10, ME68 and ME70) Fe\({}^{3+}\) preferentially, while in others (GEL1, GEL8, GEVN7, GEVN16, ME67 and ME133) a mixture of both phases. This is visible both in the pre-edge (panels in Figure 2a,b) and edge analysis (Figure S2). XANES Fe-K edge maps collected on ME68, ME70, GEVN7, GEVN16, GEL2 and GEL5 samples in cross-section geometry add further information to the point XANES spectra. We collected XRF maps at different energies across Fe K-edge. After normalization, we could discriminate whether Fe\({}^{3+}\) is the dominant phase by differentiating energies E1 and E2 in Figure S3. The processing is shown in Figure 3, where each differential map is depicted beside its corresponding Fe maps acquired at 18 keV in cross-section geometry. GEVN7 shows a sharp gloss layer where the ratios between the abovementioned energies  
Figure 1: RGB correlation considering relevant elemental markers in cross-section geometry for (**a**) Attic (GEVN9, 100 \(\times\) 500 \(\upmu\)m), (**b**) Laconian (GEL5, 150 \(\times\) 500 \(\upmu\)m), (**c**) Sicilian (GEVN15, 100 \(\times\) 500 \(\upmu\)m), (**d**) Chalcidian (ME68, 150 \(\times\) 500 \(\upmu\)m) and (**e**) Locrian (?) (GEVN10, 150 \(\times\) 500 \(\upmu\)m) products. implies a combination of both Fe\({}^{2+}\) and Fe\({}^{3+}\), followed by GEVN16 where Fe\({}^{2+}\) is present but in less proportion. It is followed by GEVN10 and GEL2, where the gloss layer is less defined (see corresponding Fe map) and finally ME68, where the ratio varies along the gloss layer indicating a slight inhomogeneity between the Fe\({}^{2+}\) and Fe\({}^{3+}\) distribution. In GEL2 and ME70 the ratio between the two energies is smaller, highlighting a more pronounced predominance of Fe\({}^{3+}\) over Fe\({}^{2+}\). Overall, the Fe XANES maps confirm the single point XANES spectra but allow a better special visualization of the distribution of the ratio between the two phases. Zn-edge XANES spectra were also collected in cross-section mode on a sub-set of the glosses exhibiting Zn on the gloss surface. All of them show a very similar spectrum (Figure 4), which can be mainly attributed to ZnAl\({}_{2}\)O\({}_{4}\) (Figure S4). Point XANES spectra were collected also on other glosses (ME67, ME70 and ME133). Even if the spectra turned out to be noisy due to lower Zn content they also confirm the presence of mainly ZnAl\({}_{2}\)O\({}_{4}\). XANES Zn-K edge maps collected on GEVN10, GEVN16, ME68--as example of the so-called Chalcidian products (southern Calabria and the Strait of Messina area)--show a predominance of ZnAl\({}_{2}\)O\({}_{4}\) along all the gloss surface layer, as also found in [43]. Figure 5 shows the Zn XRF maps in all three samples and the obtained distribution of ZnAl\({}_{2}\)O\({}_{4}\) phase, shown in red in panels a, b and c, respectively. The last image was obtained by differential imaging evaluating the ratios between different peaks identified from reference standards spectra (Figure S4), as successfully used in [44]. In particular we evaluated the ratios between the peaks 3 to 2, 3 to 1 and 2 to 1, which turned out to be bigger than one for the first two ratios and very close to one for the last one, confirming ZnAl\({}_{2}\)O\({}_{4}\) phase on the surface. Figure 2: Fe-XANES spectra acquired on a 3 \(\upmu\)m \(\times\) 4.2 \(\upmu\)m spot on the gloss layer of the samples indicated in the legend, all mounted in cross section geometry. Samples of panels (**a**) exhibit a mixture of both Fe\({}^{2+}\) and Fe\({}^{3+}\), while samples on panel (**b**) mainly Fe\({}^{3+}\).