Rapid and Semi-automated Method for Analysis of the Number of Atoms of Ultra-small Platinum Clusters on Carbon
J.C. Yang a1, S. Bradley a2andJ.M. Gibson a1 a1 Frederick Seitz Materials Research Laboratory, University of Il
linois at Urbana-Champaign, Urbana, IL 61801 a2 UOP LLC, 50 East Algonquin Road, Des Plaines, IL 60017
Very high angle (~100 mrad) annular dark-field (HAADF) images in a dedicated scanning transmission electron microscope (STEM) can be used to quantitatively measure the number of atoms in a cluster on a support material. We have developed a computer program which will automatically find the location of the particles and then integrate the intensity to find the number of atoms per cluster. We have examined ultra-small Pt clusters on a C substrate by this novel mass-spectroscopic technique. We discovered that the Pt clusters maintain their three-dimensional shape, and are probably spherical.