Unhindered Brownian Motion of Individual Nanoparticles in Liquid-Phase Scanning Transmission Electron Microscopy.

Liquid-phase transmission electron microscopy (LPTEM) offers label-free imaging of nanoparticle (NP) processes in liquid with sub-nanometer spatial and millisecond temporal resolution. However, LPTEM studies have reported only on NPs moving orders of magnitude slower than expected from bulk aqueous liquid conditions, likely due to strong interactions with the LPTEM liquid-enclosing membranes. We demonstrate how scanning transmission electron microscope (STEM) imaging can be used to measure the motion of individual NPs and agglomerates, which are not hindered by such interactions.