Particle clustering atomic force microscopy

Cover Illustration Atomic force microscopy image of molybdenum oxide particles on flat, silicon dioxide substrate, which serves as a model system for a supported catalyst. The area shown corresponds to one square micrometer the maximum difference in height is approximately 10 nanometer. The superimposed curve is the secondary ion mass spectrum of the model catalyst, showing the caracteristic isotopic patterns of single molybdenum ions and of molybdenum oxide cluster ions. 

Clusters deposited on a substrate surface are often either obtained via chemical reduction of metals in a surface catalyzed technique or by deposition from solution or gas phase. These colloids are of a typical size around HOO nm. To study these clusters electron microscopy (EM), surface tunneling microscopy (STM), atomic force microscopy (AFM) or optical near field techniques (e.g. SNOM) directly access size, shape and electro -optical properties of individual colloidal particles. 

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