Extended Data Fig. 8: Further SEM and AFM scans.
From: Spontaneous ordering of identical materials into a triboelectric series
a, We find no visible changes in the surface integrity between SEM scans of the 2,000-contact sample (left) and the plasma-treated sample (right); regions with specks are shown intentionally to aid visualization. b, With AFM, the 2,000-contact sample appears visually indistinguishable from 200-contacted or pristine samples. However, plasma treatment smoothes the roughness to an extent that is visibly apparent. c, We compare the radial PSD for pristine, 200-contact, 2,000-contact and plasma-treated samples. More contacts progressively smooth the spatially high-frequency features and the plasma treatment changes the roughness across all length scales.
