Reduced force gradient (-dFred/dz) curves with and without illumination for both facets. Note that panels a-f show the total force gradient as measured, whereas panels g-i show the reduced force gradient after subtraction of the van der Waals attraction (kTot-kvdW). All force maps are recorded on the same BiVO4 particle with the same probe with tip radius = 14.5 ± 2 nm. Corresponding NP topography images are shown inFigure S5.
