Positive Material Identification (Alloys):
XRF (X-ray Fluorescence Spectroscopy): A method of PMI using a portable X-ray fluorescence analyser to verify the chemical elements that establish the positive identification for a particular material. When activated on a test item, an XRF analyser produces short wavelength electromagnetic rays. These emitted rays interact with (excite) certain elements. As a result, the excited elements then re-emit a new wavelength within a discrete energy band that is identifiable by the analyser. When used along with material standards, the portable analyser can determine the approximate chemical quantities for the target elements.
Positive Material Identification (Carbon):
OES (Optical Emission Spectroscopy): Also called atomic emission spectroscopy (AES) or arc spark emission spectroscopy, is an important tool for fast and accurate elemental analysis of metals and semiconductors, whereby, an electric arc is used to excite electrons in a sample and cause them to emit light. The light intensities of the actual measurement are compared with the intensities of known samples which were measured from the preparation of the calibration curves. An electric arc (burn spot) stimulates atoms in the test sample to emit a characteristic spectrum of light for each element in the sample. The light enters a grating and the wavelength and intensity of each line is analyzed giving either a spectral match or an elemental percentage.