Automated detection of particles, clusters and islands in scanning probe microscopy images

In order to obtain quantitative information from scanning tunnelling micros copy (STM) images, image processing and pattern recognition techniques are very valuable tools. We developed an algorithm which automatically determin es the positions and sizes of small particles and other nanostructures in S TM and atomic force microscopy (AFM) images. This algorithm has been tested and used both in the study of Pd nanoparticles supported on TiO2 and in th e study of diffusing In atoms embedded in a Cu surface. First the original STM image is filtered in order to obtain an image of the background. Subtra cting this 'background' image from the original image eliminates the height variations in the substrate, such as atomic steps. The particles can then be found by discrimination with respect to a threshold height. Once the par ticles are located, their exact position and size are determined and used f or further analysis. (C) 2001 Elsevier Science B.V. All rights reserved.