A new view on chemistry of solids in solution-cryo energy-filtered transmission electron microscopy (cryo-EFTEM) imaging of aggregating palladium colloids in vitreous ice

It is shown that by using cryo-transmission electron microscopy (cryo-TEM) it is possible to image the aggregation behaviour of nanoparticles while th ey are still in solution. This technique has allowed the study of the arran gement of colloidal palladium particles in solution by preparing the specim en by the plunge-freezing technique, This method of rapidly cooling the spe cimen avoids rearrangement of the particles during specimen preparation. Th e palladium particles were identified by energy-filtered cryo-TEM. The aggr egation of particles in solution was studied as a function of pH and ionic strength. The results can be used as recommendations for colloidal solution s intended for deposition of single particles.