Specimen preparation technique for high resolution transmission electron microscopy studies on model supported metal catalysts

SUMMARY A new technique is described which can be used for preparing transmission electron microscopy (TEM) specimens suitable for high resolution studies on supported metal catalysts. By conventional silicon processing techniques 200 × 200 μm2 Si3N4 membranes on Si wafers are produced. These membranes are extremely flat and have a uniform thickness of 13 nm. They can be used as a support in various kinds of thin film deposition. A TiO2 film, optimally structured with respect to the requirements for high resolution TEM work in TiO2–metal cluster systems, is deposited on the Si3N4 layer. It consists of one monolayer of 10–25 nm TiO2 crystallites. TiO2 lattice images show that a line resolution down to 0.19 nm is possible. Examples of TiO2–Pd and TiO2–Rh are given using respectively photodeposition and impregnation reduction to produce l.5–4 nm metal clusters.