Spectrum Match

Spectrum Match is a powerful software program that allows the user to search through a custom built spectrum library to find similar spectra. This greatly simplifies identification of unknowns by comparing them to a group of potential candidates and reduces the complexity of finding discrepancies and similarities between spectra.

Spectrum Match
Figure 1. Spectrum matching uses
either Chi-Square fit on the spectrum
intensities or Chi-Square fit on the
concentration results.

Spectrum Match is a versatile tool with a multitude of applications, including:

  • Failure analysis and quality control - defects can be compared to a library of potential contaminants.
  • Process control - changes in distribution and composition can quickly be identified 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.

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.

Figure 2. Spectrum extracted from map visibly and numerically identifies this phase as SbS with a much high fit % compared to CaSO4, even though they contain common elements.

The matching of the active spectrum to those found in the library file is based on a chi-squared goodness of fit test, comparing either concentrations or spectra directly (Figure 1). The match sensitivity is adjustable, giving the user full control over the match results, ranging from completely identical to roughly in the same ballpark. The potential matching spectra are overlaid on the original spectrum with the match percentage giving a measure of how similar or dissimilar the spectra are along with a visual representation of the differences. Figure 2 shows an example spectrum with two overlaid spectra with a match value of 81.53% for SbS and 62.64% for CaSO4. A visual inspection quickly tells us that the discrepancies between the sample and the best matching spectrum are to be found in the Si, Ti, Ba, and Zr content.

Building a spectrum match library is made easy through the spectrum search utility. The user is able to search the full database of spectra stored on the system either through manual selection of specific project nodes or by adding filters to identify spectra with the desired characteristics. The filters include:

  • Acquisition date
  • Presence of given elements (with range in atomic %, weight % or net intensity)
  • Sample name
  • kV used

Once the spectra are selected, they are saved to a Spectrum Match library file, which can be shared among users and systems. It is even possible to add all data in the system database to a Spectrum Match library file in order to finally answer the nagging question of “Hmm, where did I see this before?”

Smart Materials and Minerals Library

The EDAX Smart Materials and Minerals Library option provides 150 entries of common metal standard alloys and minerals. The library includes:

  • 90 steel spectra
    • - Stainless steels
    • - Alloy steels, Ni-based, Cu-base alloys
    • - Tool steels
    • - Carbon steels
  • 50+ silicates and other geological standard materials
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