Harmonic force microscopy images. Height (A, C) and corresponding elasticity images (B, D) of α-synuclein fibrils on mica. E represents the cross-sections drawn over the fibril in C. F represents the cross-section from D and shows a few scan artifacts. The background, mica, has here a stiffness of ± 1.5 GPa, probably caused by the limited range of elastic moduli which can be measured with the chosen cantilever. The peaks shown around 80 and 120 nm are edge effects caused by changing contact areas. The dip around 100 nm is assumed to be relevant for averaging and used to determine a modulus of elasticity. Scale bars are 250 nm.