Berlin 2012 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MM: Fachverband Metall- und Materialphysik

MM 5: Transport and Diffusion I

MM 5.4: Vortrag

Montag, 26. März 2012, 11:00–11:15, H 1029

Quantitative measurement of the surface diffusion on metallic nanoparticles by aberration-corrected HRTEM — •Alexander Surrey, Darius Pohl, Ludwig Schultz, and Bernd Rellinghaus — IFW Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany

Aberration-corrected high-resolution transmission electron microscopy (HRTEM) allows for the investigation of the atomic diffusion on the surface of a nanoparticle in particular during the coalescence of adjacent particles. The incident electron beam may effectively promote this sintering process, although so far, it is not yet known to which extend. Since the material transport during the inter-particle coalescence occurs via surface diffusion, a quantitative determination of the latter is needed. Thus in the present study, the motion of atoms at the surfaces of Au nanoparticles is characterized by means of aberration-corrected HRTEM with the resolution of individual atomic columns. Subjects of the analysis are Au icosahedra on amorphous carbon substrates and single crystalline Au octahedra whose surfaces extend into the vacuum and which are thus imaged "without a substrate". A method is developed which allows for a quantitative estimation of the diffusion coefficient based on the measured temporal fluctuation of the occupation of individual atomic surface columns as obtained from HRTEM images. The likewise derived coefficient of the surface self-diffusion is in very good agreement with the results of atomic force and scanning tunneling microscopy studies.