Video-frequency scanning transmission electron microscopy of moving gold nanoparticles in liquid

► We introduce a method to operate scanning transmission electron microscopy (STEM) at video frequency, which allows us to achieve high contrast and a resolution of 1.5 nm on gold nanoparticles in liquid. ► We studied the movement of nanoparticles in liquid and compare these results with calculations of Brownian Motion. ► We conclude that the observed movements are three orders of magnitude smaller than expected on the basis of Brownian Motion.