In this physical chemistry lab experiment, students use atomic force microscopy to investigate the surface of graphite (organic) and gold (inorganic) samples (solid phase) to compare topographical features, surface roughness, and adhesion forces of the samples. Carbon surfaces are ubiquitous in various fields, and the surface reactivity can be altered by surface functionalization on the molecular scale, introducing functional groups, thus shifting their macroscale properties. Surface chemistry impacts technology, advancing the development of new heterogeneous catalysts, semiconductor devices, and materials synthesis. The surface of each OSD is explored through students’ collection and interpretation of topographic and force curve data using an AFM to identify differences in the structure of the grooves containing pits and lands, estimation of theoretical storage capacity, and finally distinguish OSD types by comparing their data and calculations to known structures and capacities. The guided inquiry investigation presented here introduces students to the design and basic functions of an AFM through their identification of three unknown OSD samples (CD, DVD, or Blu-ray). They can, consequently, serve as a relevant phenomenon for undergraduate students to explore nanoscale material structure and macroscopic function through an AFM. Optical storage discs (OSDs) coevolved with AFM technology, are relatively inexpensive, and are easily available for purchase. As the “hands and eyes of the nanoworld”, atomic force microscopes (AFMs) continue to be used to innovate the nanowriting process for data storage and in the exploration of novel materials suitable for ultrafast, nonvolatile, high density memory storage. Scanning probe microscopy such as atomic force microscopy has become increasingly integrated and relevant in undergraduate laboratory investigations. The open design of the model can easily accommodate additional capabilities in which students are interested, e.g., topographical scanning and using cantilevers made from different materials.
Through completion of this project, students learned scientific instrument design and construction via 3D printing and obtained first-hand practice in the measurement of force–distance profiles and the elastic constants of cantilevers. The model AFM was designed, printed, and used by first- and second-year undergraduate students.
Using a magnet attached to the tip of the cantilever and a metal sample, this model AFM enables acquisition of force–distance profiles with characteristic snap-in, pull-off, separate, and contact regions. The model has many of the key parts of an actual AFM including a z-axis stage, an AFM head with a cantilever assembly, and a laser source that reflects off of the back of the cantilever. We report a simple means to build a model atomic force microscope (AFM) using 3D printing of thermoplastic materials that are commercially available.
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