a SEM micrograph of printed AgNPs and schematic showing PVP coordination on a single AgNP surface. b PCA scores and c loadings of depth profiling data at nanoparticle depth resolution. The dashed rectangle represents d depth profile within 100 nm showing signals for secondary ions C6H10NO+, C4H7+, C6H11NOAg+ and Ag+. e XZ maps within a depth of 80 nm. The data are averaged over an area of 100 × 100 µm2 per depth level.