ABSTRACT
Electron microscopy of Ag-Ru and Cu-Ru bi-metallic catalysts in MCM-41 i carried out in a dedicated field emission gun scanning transmission electron microscope (VO HB501). The distinctive advantage is that the beam damage is limited to scanned area since onl the part of the sample that the investigation is being carried out is exposed to electrons; this in not necessarily the case in a conventional TEM. This negates the more conventional wisdom tha the intense probe will damage the material before it can be investigated. Other advantages c using STEM are more conventional: high resolution analytical analysis of the catalyst particles i possible using the sub-nanometer probe and high angle annular dark field (Z-contrast) imagin allows the analysis of the distribution and homogeneity of the particles within channels mor readily then any other method. Examples of the application are shown for Ag-Ru and Cu-Ru bi metallic particles in MCM-41. Inferences are also drawn in terms of the number of particle superposed or clumped together inside the channels.
