The position and size of the candidate particles are recorded automatically. A revisit by the electron beam is used to analyze the particle. The emitted X-ray spectrum of each particle is classified using the choice of either Regions of Interest (ROI) or Spectrum Stripping spectrum analysis (STRIP) classification schemes.

Classification scheme for fixed and user definable classes.

Classification scheme for fixed and user-definable classes

The ROI classification scheme uses ratios of ROI counts data to determine the elements present in the spectrum. The ROI scheme classifies each spectrum into one of 35 categories in accordance with the Metropolitan Police GSR classification scheme. It is possible to select different classes or configure the selected classes. Up to 35 user-definable classes can be set for each run. Saving the settings as different configuration files can increase the number of definable classes. The STRIP classification scheme performs full background subtraction and iterative peak stripping to derive intensity data for the elements present in the spectrum. This classification scheme allows classes to be constructed by the user according to tight or wide chemical criteria, so that both fixed stoichiometric compounds can be identified, as well as continuous-composition phases typical of GSR particles. After a run, particles can be revisited and reanalyzed using a new, perhaps longer, acquisition-time spectrum, and then reclassified. The reclassified data are merged with the original data but preserving the original classification. In addition, whole runs can be reclassified automatically should the user decide to change or add a class definition to the classification scheme.