Scanning probe microscopy-how does it work and what might you use it for?

In 1986, IBM were rewarded with one of the ultimate scientific accolades, a Nobel Prize: Binnig and Rohrer were awarded the Physics Prize for their discovery of the scanning tunnelling microscope. This was the birth of a series of techniques which has become an exciting new area of analytical science-the field of scanning probe microscopy (SPM). Since the mid eighties, the field of SPM has developed into a broad family of techniques enabling the surface scientist to reach a better understanding of the surface topography of his particular material. Whether he be working with a polymer, a semiconductor or a biomaterial, the field of SPM has opened up a whole new range of ways to study the surface of a material and its properties. SPM is defined generically as follows: a technique that involves the movement of a probe across a surface to generate an image representative of a specific physical property of the surface under study. The author considers a number of techniques from the family of SPM. A brief description is given of each together with examples of its use in surface characterisation. 1) Scanning tunnelling microscopy; 2) atomic force microscopy; 3) magnetic force microscopy; 4) scanning thermal microscopy; 5) near-field scanning optical microscopy. This is by far from being the full family of techniques available. When considering an experiment, the user has many experimental variables for consideration. Should the experiment be carried out in air, in vacuum or in liquid. For many applications, particularly those in the study of biomaterials, it is important to image under liquid to enable the sample to remain in its natural state, e.g. the imaging of a chromosome. A more complex liquid study could be to set up the imaging cell for electrochemical studies. In such cases, the experimenter may study such phenomena as deposition and corrosion