## 4 Conclusions
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{3}{c}{**G4**} \\ \hline
**Binding Energy (eV)** & **Counts** & **S/N Ratio** & **Spectral Line** & **ID** & **CAS Registry No.** \\ \hline
779.8 & 261,185 & 43 & Ba 3d5/2 & BaO, BaCO\({}_{3}\) & 1304-28-5, 513-77-9 \\
530.4 & 625,698 & 104 & O 1s & -O, -CO\({}_{3}\) & multiple \\
401.3 & 4233 & - & Sc 2p3/2 & Sc\({}_{2}\)O\({}_{3}\) & 12060081 \\
379.2 & 5299 & - & K 2s & K- & 7440-09-7 \\
351.1 & 37,681 & 5 & Ca 2p1/2 & CaCO\({}_{3}\) & 1304-28-5, 513-77-9 \\
306.8 & 155,458 & 25 & Mg KLL & Mg- & Ref. [18] \\
293.8 & 24,400 & 3 & K 1s & K- & 7440-09-7 \\
288.4 & 57,337 & 8 & C 1s & -CO\({}_{3}\) & multiple \\
284.6 & 224,074 & 37 & C 1s & C (Adv.) & multiple \\
251.4 & 14,893 & - & Ba 4s & - & 1304-28-5, 513-77-9 \\
177.7 & 44,757 & 6 & Ba 4p3/2 & Ba- & 1304-28-5, 513-77-9 \\
153.8 & 107,985 & 15 & Si 2s & SiO\({}_{2}\) & 7631-86-9 \\
119.0 & 33,001 & 3 & Al 2s & Al- & 1344-28-1 \\
102.8 & 125,224 & 18 & Si 2p & SiO\({}_{2}\) & 7631-86-9 \\
89.8 & 82,798 & 11 & Ba 4d5/2 & BaO, BaCO\({}_{3}\) & 1304-28-5, 513-77-9 \\
74.3 & 22,213 & 2 & Al 2p3/2 & Al\({}_{2}\)O\({}_{3}\) & 1344-28-1 \\
49.9 & 24,683 & 2 & Mg 2p & Mg- & 7439-95-4 \\
28.6 & 21,599 & 2 & Ba 5s & Ba- & 1304-28-5, 513-77-9 \\
24.8 & 39,232 & 4 & Ca 3p & Ca- & 1305-78-8, 471-34-1 \\
13.0 & 11,826 & - & Ba 5p3/2 & BaO & 1304-28-5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: XPS data for point G4. Binding energy and counts taken from the overview spectra. S/N ratios were computed manually. A “-” indicates an S/N ratio below 1.5, implying signal indistinguishable from background. Spectral line and ID were taken from the NIST XPS Database [22]. See text for details. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**G6**} \\ \hline
**Binding Energy (eV)** & **Counts** & **S/N Ratio** & **Spectral Line** & **ID** & **CAS Registry No.** \\ \hline
779.8 & 1,610,507 & 313 & Ba 3d5/2 & BaO, BaCO\({}_{3}\) & 1304-28-5, 513-77-9 \\
530.4 & 638,247 & 123 & O 1s & -O, -CO\({}_{3}\) & multiple \\
401.3 & 8617 & - & Sc 2p3/2 & Sc\({}_{2}\)O\({}_{3}\) & 12060081 \\
379.2 & 9488 & -0 & K 2s & K- & 7440-09-7 \\
351.1 & 11,285 & -0 & Ca 2p1/2 & CaCO\({}_{3}\) & 1304-28-5, 513-77-9 \\
306.8 & 20,069 & 2 & Mg KLL & Mg- & Ref. [18] \\
293.8 & 16,358 & - & K 1s & K- & 7440-09-7 \\
288.4 & 112,395 & 20 & C 1s & -CO\({}_{3}\) & multiple \\
284.6 & 73,582 & 12 & C 1s & C (Adv.) & multiple \\
251.4 & 60,804 & 10 & Ba 4s & Ba- & 1304-28-5, 513-77-9 \\
177.7 & 181,032 & 33 & Ba 4p3/2 & Ba- & 1304-28-5, 513-77-9 \\
153.8 & 15,477 & - & Si 2s & SiO\({}_{2}\) & 7631-86-9 \\
119.0 & 57,889 & 9 & Al 2s & Al- & 1344-28-1 \\
102.8 & 35,347 & 5 & Si 2p & SiO\({}_{2}\) & 7631-86-9 \\
89.8 & 508,840 & 97 & Ba 4d5/2 & BaO, BaCO\({}_{3}\) & 1304-28-5, 513-77-9 \\
74.3 & 5132 & - & Al 2p3/2 & Al\({}_{2}\)O\({}_{3}\) & 1344-28-1 \\
49.9 & 8596 & - & Mg 2p & Mg- & 7439-95-4 \\
28.6 & 26,415 & 3 & Ba 5s & Ba- & 1304-28-5, 513-77-9 \\
24.8 & 19,788 & 2 & Ca 3p & Ca- & 1305-78-8, 471-34-1 \\
13.0 & 54,584 & 8 & Ba 5p3/2 & BaO & 1304-28-5 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: XPS data for point G6. Binding energy and counts taken from the overview spectra. S/N ratios were computed manually. A “-” indicates an S/N ratio below 1.5, implying signal indistinguishable from background. Spectral line and ID were taken from the NIST XPS Database [22]. See text for details.