Back-Reflection XRD Apparatus for Unprepared Sample Analysis
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Solution Overview
Problem
Conventional X-ray diffraction techniques are sensitive to sample morphology, making it difficult to analyze unprepared samples, such as whole rocks or precious artifacts, as they require a uniform powder form, which can be damaging and limits their application in fields like geology and archaeology.
Innovation Solution
A method and apparatus for energy-dispersive X-ray diffraction using a beam of X-ray radiation with a range of photon energies, obtaining energy-resolved spectra with different settings to exclude fluorescence signals, allowing for diffraction information independent of fluorescence phenomena, and utilizing a back-reflection geometry with a diffraction angle of 180° to reduce sensitivity to sample distance and morphology, enabling analysis of non-prepared samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional X-ray diffraction techniques are used, then diffraction analysis can be performed, but the technique is sensitive to sample morphology requiring uniform powder form
Solution Approach 1:
The patent changes the detection parameter from angle-dispersive to energy-resolved detection, and introduces multiple energy settings to suppress fluorescence signals. This allows analysis of unprepared samples with various morphologies while maintaining diffraction analysis capability through fluorescence suppression at different energy settings.
2Quantity of substance
If fluorescence signals are present in the spectra, then complete energy range can be measured, but diffraction information is obscured by fluorescence phenomena
Solution Approach 1:
The patent segments the energy measurement range by taking spectra at multiple different energy settings. Each spectrum captures diffraction information in specific energy ranges where fluorescence is suppressed, and these segmented spectra are combined to reconstruct the complete diffraction pattern across the full energy range.
Solution Approach 2:
The patent uses periodic action by alternating between different energy settings to acquire spectra. The source energy is periodically changed to different values, allowing systematic suppression of different fluorescence signals and enabling reconstruction of complete diffraction information.
3Reliability
If back-reflection geometry with 180° diffraction angle is used, then sensitivity to sample distance and morphology is reduced, but instrument construction becomes more compact
Solution Approach 1:
The patent inverts the conventional diffraction geometry by using back-reflection at 180° instead of forward scattering. This inversion makes the diffraction measurement insensitive to sample distance and morphology variations, improving reliability while enabling compact instrument design.
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
This approach allows for the analysis of unprepared samples with improved signal strength and reduced sensitivity to sample morphology, enabling the analysis of whole rocks and other non-prepared materials, and provides a compact, portable instrument capable of suppressing fluorescence signals, thereby obtaining diffraction information over a wider range of energies.
Implementation Method 1
Powder X-ray diffraction (XRD) is a well-known technique for analysis of crystalline materials. In ADXRD, an X-ray beam with, ideally, a single wavelength λ is diffracted by a sample through a range of distinct scattering angles 2θ, according to the Bragg equation: λ=2d sin θ
Implementation Method 2
a plurality of energy-resolved spectra are obtained using different settings of source energy, whereby at least one of said spectra excludes a fluorescence signal that is present in another of said spectra
Data Source
AI summary
Methods and apparatus are provided for performing back-reflection energy-dispersive X-ray diffraction (XRD). This exhibits extremely low sensitivity to the morphology of the sample under investigation. As a consequence of this insensitivity, unprepared samples can be analyzed using this method. For example, in a geological context, whole rock samples become amenable to analysis. A composite diffraction spectrum can be produced using information from different recorded spectra in different energy sub-ranges. The composite spectrum excludes fluorescence signals that would otherwise obscure the diffraction signals.