Wavelength Dispersive X-Ray Fluorescence Peak Intensity Deconvolution
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Solution Overview
Problem
Wavelength-dispersive X-ray fluorescence spectrometers face challenges in accurately determining the intensity of the analytical signal due to overlapping signal components from different diffraction orders and interference from detector noise, escape radiation, and pile-up effects in the pulse height spectrum, leading to inaccurate estimates.
Innovation Solution
A computer-implemented method generates a pulse height spectrum model that includes diffraction order and escape profiles, adjusted using a fitting algorithm to minimize differences with the measured spectrum, allowing for the accurate determination of the first-order peak intensity and contribution areas of higher diffraction orders, thereby improving linearity and resolving goniometer measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed integration region is used to estimate the intensity of the first order peak, then the measurement process is simple, but the accuracy of the analytical signal intensity is poor due to superposed contributions from higher diffraction orders
Solution Approach 1:
The pulse height spectrum is segmented into multiple components corresponding to different diffraction orders (first order, second order, third order, etc.). Each diffraction order contributes a distinct profile to the total spectrum, and the method separates these profiles mathematically to isolate the first order peak intensity from contributions by higher orders.
Solution Approach 2:
The method changes the approach from using a fixed integration region to a dynamic deconvolution process that adjusts for varying contributions from higher diffraction orders. By modeling the spectrum as a sum of individual diffraction order profiles with adjustable parameters, the method adapts to different spectral conditions and accurately extracts the first order intensity regardless of higher order interference.
2Quantity of substance
If higher diffraction orders are allowed to reach the detector, then more signal components are captured, but the accuracy of analytical signal determination deteriorates due to signal overlap
Solution Approach 1:
The method extracts the contribution of higher diffraction orders from the total pulse height spectrum through mathematical deconvolution. By modeling and subtracting the profiles corresponding to second, third, and higher diffraction orders, the method isolates the pure first order peak intensity, effectively taking out the interfering components from the measurement.
3Loss of information
If detector escape radiation is present, then additional peaks appear in the spectrum, but the accuracy of peak intensity measurement is reduced due to interference
Solution Approach 1:
The method introduces an escape profile model as an intermediary component in the spectral decomposition. This model represents the escape radiation contribution separately, allowing the algorithm to account for and subtract escape peak interference from the main analytical peak intensity measurement, thereby recovering the true signal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method effectively separates the contributions of different signal components, enhancing the accuracy of analytical signal intensity measurement and reducing the influence of Bremsstrahlung background, thereby improving the resolution and linearity of the spectrometer.
Implementation Method 1
the radiation reflected by a monochromator of the spectrometer (typically a crystal) at various diffraction angles θ. This technique is based on Bragg's law where n is the diffraction order, λ the wavelength and d the lattice plane distance of the monochromator.
Implementation Method 2
When a photon hits the detector of the spectrometer, the photon is eventually converted into an electric pulse where the pulse height is proportional to the energy of the photon.
Implementation Method 3
with the initial absorption of the x-ray photon, the detector material itself generates fluorescence radiation that can leave the detector and thus diminishes the pulse height registered (measured) by the detector. This is called escape and causes an additional peak at lower energies in the pulse height spectrum.
Data Source
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AI summary
System (100), method and computer program product for estimating peak intensities in pulse height spectra obtained by wave-length dispersive x-ray fluorescence spectrometers are disclosed. A pulse height spectrum (212) is obtained by a multi-channel analyzer (205) of a wavelength-dispersive X-ray fluorescence spectrometer (200) from a sample (202). A model generator (120) generates a pulse height spectrum model (112) by creating a plurality of diffraction order profiles with predefined profile shapes at photon energy positions corresponding to respective diffraction orders of a monochromator (203) of the spectrometer (200). For each created diffraction order profile where the corresponding photon energy is higher than the edge energy of the detector material of the detector, a respective escape profile is added. A model adjustment module (130) adjusts pulse-height-to-energy-mapping parameters and contribution area of each diffraction order profile ensemble of the pulse height spectrum model using a fitting algorithm (FA1) to minimize the difference between the pulse height spectrum model (112) and the measured pulse height spectrum (212). An intensity module (140) provides the contribution area of the first order profile ensemble as the intensity (El1) of the energy to be determined by the wavelength-dispersive X-ray fluorescence spectrometer (200).