8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.171Tomographic cryo-TEM of colloidal nanoparticledispersionsJos van Rijssel, 1 Albert P. Philipse, 1 and Ben H. Erné 11 Van ’t Hoff laboratory, Utrecht University, Padualaan 8, 3584 CH, Utrecht, NetherlandsA powerful technique to study colloidal interactions is confocal laser scanning microscopy. Fromthe observed 3D positions of colloids in liquid dispersion, interaction potentials and thermodynamicquantities can be determined. [1] To obtain similar information for colloidal particles toosmall to be resolved by optical microscopy, we use cryogenic transmission electron microscopy(cryo-TEM). Our colloidal model system consists of monodisperse PbSe nanocrystals of 5 to 10nm dispersed in apolar solvent. Snapshots of particle positions are obtained in 2D or in 3D, usingtilt series and tomographic reconstruction. By quantitative image analysis, radial distributionfunctions and cluster size distributions are obtained. Interpretation using a thermodynamicequilibrium model yields the interaction free energy, which is further split into its enthalpic andentropic components using temperature dependent data. The effects of particle size and solventquality are currently under study. Our ultimate aim is to characterize the nature and strength of theinteractions between colloidal nanoparticles that self-assemble into colloidal crystals.[1] Roel P. A. Dullens et al. , PNAS, 103 - 529(2006).171