X-Ray Spectrum Difference Analysis for Chemical State Identification
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Solution Overview
Problem
Conventional spectral analysis methods face difficulties in accurately distinguishing chemical state changes from self-absorption effects due to shifts in absorption edges when varying the accelerating potential of an electron beam, particularly for transition metals.
Innovation Solution
A sample analysis apparatus and method that normalizes intensity spectra by equalizing the intensity at the top of a reference peak and calculates difference spectra, using a database to identify compounds and states based on these normalized and difference spectra, thereby reducing the influence of absorption edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the accelerating potential of the electron beam is varied to obtain intensity spectra, then the chemical bonding state and composition of the sample can be analyzed, but absorption edges cause peak energy shifts that make it difficult to distinguish between chemical state changes and self-absorption effects
Solution Approach 1:
The patent extracts the absorption edge effect from the intensity spectrum by calculating a difference spectrum between two intensity spectra obtained at different accelerating potentials. This separates the absorption-related information from the chemical state information, allowing the latter to be analyzed without interference from the former.
Solution Approach 2:
The patent uses two different accelerating potentials (excessive action) to obtain two intensity spectra. By using more than one measurement condition, the absorption edge effects can be differentiated from chemical state information through comparison and difference calculation.
2Ease of operation
If conventional fingerprinting method is used for sample analysis, then the composition and state of the sample can be identified by comparing with database, but the method becomes ineffective when absorption edges are present near peaks of interest
Solution Approach 1:
The patent changes the parameter used for identification from the original intensity spectrum to a difference spectrum. This parameter transformation eliminates the absorption edge interference while preserving the chemical state information, making the fingerprinting method reliable even when absorption edges are present.
3Device complexity
If intensity spectrum is used directly for identification without normalization, then the analysis process is simple, but variations in accelerating potential cause peak shifts that reduce identification accuracy
Solution Approach 1:
The patent performs preliminary normalization of the intensity spectra before calculating the difference spectrum. This preliminary action corrects for variations in accelerating potential and ensures that subsequent difference calculation accurately reflects chemical state information without peak position errors.
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
Enables accurate sample analysis by eliminating the impact of absorption edges, allowing for precise identification of compounds and their states even when the accelerating potential of the electron beam is varied.
Implementation Method 1
By irradiating an electron beam onto a sample and spectrally dispersing characteristic X-rays emitted from the sample
Implementation Method 2
By irradiating an electron beam onto a sample
Implementation Method 3
JP S63-39855 U discloses a technique of calculating an absorption spectrum from a difference between two intensity spectrums
Data Source
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AI summary
Spectrums are measured by irradiating an electron beam on a sample while varying an accelerating potential and by detecting X-rays emitted from the sample. A normalizer unit (94A) normalizes the spectrums and thereby calculates normalized spectrums. A difference calculator unit (94B) calculates difference spectrums based on the normalized spectrums. A search unit (96B, 98B) performs a search in a database (100) for each comparison difference spectrum, and identifies compounds contained in the sample.