Spectrum Match from EDAX is a robust software program that enables users to search through a custom built spectrum library to locate similar spectra. This significantly simplifies identification of unknowns by comparing them to a group of possible candidates and decreases the complexity of finding discrepancies and similarities between spectra.
Spectrum Match is a versatile tool with numerous applications, such as:
- Failure analysis and quality control - Defects can be compared to a library of possible contaminants.
- Process control - Changes in distribution and composition can be identified quickly with the combination of phase mapping and spectrum matching.
- Reverse engineering - Material constituents can be matched against a library of standard components found in the material.
The matching of the active spectrum to those found in the library file is founded on a chi-squared goodness of fit test, comparing either concentrations or spectra directly (refer Figure 1). The match sensitivity is adjustable, offering the user total control over the match results, ranging from completely identical to approximately in the same ballpark. The potential matching spectra are overlaid on the original spectrum with the match percentage offering a measure of how similar or dissimilar the spectra are together with a visual depiction of the differences. Figure 2 illustrates an example spectrum with two overlaid spectra having a match value of 81.53% for SbS and 62.64% for CaSO4. A visual inspection rapidly informs the user that the discrepancies between the sample and the best matching spectrum are to be found in the Si, Ba, Ti, and Zr content.
Figure 1. Spectrum matching uses either Chi-Square fit on the spectrum intensities or Chi-Square fit on the concentration results.
Figure 2. Spectrum extracted from map visibly and numerically identifies this phase as SbS with a much higher fit % compared to CaSO4, even though they contain common elements.
Designing a spectrum match library is made easy via the spectrum search utility. The user is able to search the entire database of spectra saved on the system either via manual selection of specific project nodes or by adding filters to identify spectra with the desired characteristics. The filters include:
- Acquisition date
- kV used
- Presence of given elements (with range in atomic %, weight % or net intensity)
- Sample name
After the spectra are chosen, they are saved to a Spectrum Match library file, which can be shared among systems and users. It is even possible to incorporate all data in the system database to a Spectrum Match library file so as to finally answer the irksome question of, “Hmm, where did I see this before?”
Smart Materials and Minerals Library
The EDAX Smart Materials and Minerals Library option offers 150 entries of common metal standard alloys and minerals. The library includes:
- 90 steel spectra
- Carbon steels
- Stainless steels
- Alloy steels, Ni-base, Cu-based alloys
- Tool steels
- 50+ silicates and other geological standard materials