What We See Part 1: Morphological Properties of Particles in a Fixed Mount

We often identify what we expect to see, what is familiar, or what we want to see based on limited information (1). For example, while reading we may skim a word based on the first and last letters; however, it may not be the actual word. The brain is very busy, and it often skips ahead when it comes to a conclusion based on a limited set of data. We may have to go back and view all the letters to identify the actual word. Looking at particles under the light microscope is similar. Working memory is limited at any given time and must be regularly updated while the many visible properties of a particle are examined. There are more than 40 optical properties that may be used to characterize a particle in a fixed mounting medium. Information on how the particle was generated, where it came from, how it was transported, its composition, and other aspects of its history are often written in its optical properties. A list of the morphological properties is presented here with information on how to look for them. Without such a list it is easy to overlook important characteristics that may be critical in understanding how a particle relates to the analytical questions being asked.