Advanced Background Corrections

Probe for EPMA and CalcImage provides non-linear (curved) background fitting for situations where the background cannot be interpolated using a straight line fit for both point analyses and x-ray map pixels

• Utilize exponential and polynomial fit backgrounds to obtain high accuracy trace element and low Z element analyses where the background is significantly curved.
• Plot and adjust these non-linear methods using your previously acquired wavescan samples for optimum results and apply to previously acquired standard and unknown samples.
• Single side and slope background methods are also available.
• Background models can be adjusted in post processing for maximum flexibility.

Utilize the latest state of the art background corrections with multi-point and “shared” backgrounds, developed in cooperation with microanalysis experts Michael Jercinovic, Michael Williams (University of Massachusetts), Julien Allaz (ETH Zurich) and Karsten Goemann (University of Tasmania).

• Our multi-point background acquisition allows the program to automatically acquire a specified number of off-peak intensities distributed on each side of the analytical peak, which can also be specified manually by the user, to avoid unpredicted off-peak interferences from other elements.
• Utilize up to 18 off-peak multi-point background positions on each side of the peak.
• This process is performed iteratively when the background correction is calculated, by optimizing a fit based on removing background points with the highest variances above the fitted background, until a specified number of valid background positions is reached.
• This allows the software to correctly fit the background even when an unanticipated emission line appears unexpectedly.
• Perform graphical evaluation and analysis of your Multi-Point Backgrounds using linear, polynomial and exponential fitting methods.
• Perform all these procedures during on-line acquisition or when off-line post processing.

Shared backgrounds allow the user to take advantage of the above multi-point background methods when two or more elements sharing the same spectrometer and Bragg crystal are acquired using normal two point off-peak backgrounds.

• “Share” off-peak background positions from other elements for elements which were acquired using the same spectrometer and crystal.
• Using the above described multi-point background arrays, the user can simply click the “Search For “Shared” Backgrounds button to automatically load element background intensities.
• This new method allows for much better control of the background modeling in situations where the background is complex (e.g., multiple REEs).
• This method is completely reversible with only a couple of mouse clicks to allow one to compare results from normal off-peak and multi-point background correction methods.
• Shared backgrounds can be applied to quantitative X-ray maps for maximum flexibility.

Based on Kramer’s Law (and some additional physics) the Mean Atomic Number (MAN) background correction method allows for fast, high precision analyses *without* measuring off-peak intensities. Utilizing MAN background corrections for trace element mapping, one can improve precision and cut acquisition time in half.

• Use the MAN background method for trace, minor and major element analyses, and save spectrometer wear and tear while improving your analyses.
• MAN background methods can be applied to both point analyses and X-ray map pixels quickly and easily.
• The MAN method is unaffected by typical off-peak interferences therefore improving accuracy compared to off-peak methods in many circumstances.The MAN background correction method can routinely perform background corrections on points and x-ray map pixels with an accuracy of approximately 100 to 200 PPM in silicates and oxides.
• By combining this time saving background correction technique with the “blank” correction (with a suitable blank standard, e.g., high purity elements, synthetic oxides and silicates, etc.), we can further improve the MAN background correction accuracy to the level of the measured precision. 
• And in half the acquisition time of using off-peak backgrounds!