Atomic Force Microscopy
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Atomic Force Microscopy Francesco Marinello TESAF, Dipartimento Territorio e Sistemi AgroForestali, University of Padova, Legnaro, Italy
Synonyms Scanning force microscopy
Definition Atomic force microscopy, often abbreviated as AFM, is one of the elected techniques for fine surface and geometrical characterization. Atomic force microscopes provide three-dimensional reconstruction of surface topographies with sub-nanometer vertical and lateral resolution, over a range which is typically no larger than a few tens or hundreds of micrometers. Atomic force microscopes belong to the family of scanning probe microscopy (SPM), a branch of microscopy allowing imaging of surfaces by means of a physical probe scanning the sample surface. SPMs monitor the interaction between the probe and the surface to produce an image or a three-dimensional reconstruction of the surface. SPMs classification is based on the specific physical principles causing the interaction (e.g., Marinello et al. 2010, 2014). When such interaction is a force (magnetic, electrostatic, friction,
etc.), the scanning probe microscopes are also classified as scanning force microscopes (SFMs). Atomic force microscopy is a specific kind of SFM, where the interaction is an interatomic weak force called the van der Waals force. Atomic force microscopy was firstly presented in 1986 (Binnig et al. 1986), and commercial systems have been available since 1989. Atomic force microscopy is now a mature measuring technique, implemented not only for research but also in production lines, where high-quality requirements call for high-resolution surface characterization.
Theory and Application The basic of an atomic force microscope is relatively simple in concept. Its closest predecessor is the stylus profilometer: AFM technology implements sharper probes and takes advantage of lower interaction forces to produce highresolution topography reconstruction with no damage of the sample surface. Surface topographies are then obtained by mechanically moving the probe in a raster fashion over the specimen and monitoring point by point, line by line the interaction between the probe and the surface as a function of the position. Technology An AFM typically includes the following components (Yacoot and Koenders 2011): a scanning
# CIRP 2016 The International Academy for Production Engineering et al. (eds.), CIRP Encyclopedia of Production Engineering, DOI 10.1007/978-3-642-35950-7_6577-3
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system, a probe, a probe motion sensor, a controller, a noise isolator, and a computer. The movement of the tip or sample is performed by an extremely precise positioning device, usually made from piezoelectric ceramics, most often in the form of a tube scanner. Systems based on other actuation principles, such as voice coil, are also available. The scanner is capable of sub-nanometer resolution in x, y, and z directions: it is the most fundamental component and the hearth of the microscope. Another AFM key component is the probe. The probe can be moved or stationary: in the first case, it is vert
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