SURFACE IMAGING OF THERMALLY SENSITIVE PARTICULATE AND FIBROUS MATERIALS WITH THE ATOMIC-FORCE MICROSCOPE - A NOVEL SAMPLE PREPARATION METHOD

High-resolution surface imaging by atomic force microscopy (AFM) of pa rticulate materials is often problematic, principally as a result of t he large height (z) variations in sample topography that either preven t the probe scanning over the particle or cause probe self-imaging. Th is paper reports a novel method of embedding thermally sensitive parti culate and fibrous materials which overcomes many of these problems an d facilitates AFM imaging of these difficult materials. The process in volves partial embedding of the sample in a cyanoacrylate film polymer ized at room temperature. The sample heating required in currently use d methods of particulate embedding is avoided and the method is theref ore suitable for thermolabile materials, The cyanoacrylate film provid es a flat hard surface which is ideal for AFM imaging, and the method has allowed successful imaging of relatively large particulate and fib rous samples such as starch granules and cellulose fibres. The cyanoac rylate has the added benefit that shrinkage holes in the film allow ea sy visual identification of areas where the film may have partially co vered the sample.