SEM Absorption Edge Mapping Using Dual-Voltage Spectral Ratios
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Solution Overview
Problem
Existing methods for analyzing the two-dimensional spatial distribution of an absorption edge structure of a sample are limited by the need for thin samples in TEM-EELS and large devices in XAFS, preventing wide-range observations.
Innovation Solution
A scanning electron microscope that applies individual electron beams with two different acceleration voltages to obtain electron beam excitation characteristic X-ray spectra, calculates spectral ratios, and displays the results as a spectral map.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If TEM-EELS is used to analyze absorption edge structure, then chemical bonding state can be observed, but sample must be made thin which prevents wide-range observation of bulk samples
Solution Approach 1:
The patent uses characteristic X-rays as an intermediary to transfer information about the absorption edge structure from the sample to the detector. By measuring the intensity spectrum of characteristic X-rays at different acceleration voltages and calculating spectral ratios, the system can analyze chemical bonding states without requiring the sample to be thin, thus enabling wide-range observation of bulk samples while maintaining chemical bonding analysis capability
Solution Approach 2:
The patent changes the acceleration voltage parameter of the electron beam to obtain emission spectra at different energies. By measuring spectra at multiple acceleration voltages and calculating their ratios, the system can extract absorption edge information that reveals chemical bonding states, achieving both precise chemical bonding analysis and wide-range observation capability
2Adaptability or versatility
If synchrotron radiation XAFS is used to observe absorption edge structure, then wide-range observation is possible, but large device is required which reduces accessibility
Solution Approach 1:
The patent creates a simplified copy of the synchrotron radiation XAFS measurement capability using conventional electron microscopy equipment. By using the electron beam to generate characteristic X-rays and analyzing their intensity spectra at different acceleration voltages, the system replicates absorption edge measurement functionality without requiring a large synchrotron radiation facility, thus enabling wide-range observation with accessible equipment
Solution Approach 2:
The patent replaces the complex synchrotron radiation mechanism with a simpler electron beam-based system. Instead of using synchrotron radiation to directly probe the sample, the system uses electron beam excitation to generate characteristic X-rays whose intensity spectra contain absorption edge information, substituting a mechanically complex large-scale system with a more compact and accessible alternative
3Measurement precision
If conventional X-ray spectroscopy is used for element analysis, then element identification is achieved, but absorption edge structure and chemical bonding information are lost
Solution Approach 1:
The patent employs periodic action by measuring the emission spectrum at multiple discrete acceleration voltages and calculating the ratio between these spectra. This periodic measurement approach at different energy levels reveals the absorption edge structure that contains chemical bonding information, while still maintaining element identification capability through the characteristic X-ray energy positions
Solution Approach 2:
The patent performs preliminary action by measuring the emission spectrum at a first acceleration voltage before measuring at a second acceleration voltage. The first spectrum serves as a reference that is later used to calculate the spectral ratio with the second spectrum, enabling extraction of absorption edge information that reveals chemical bonding states while preserving element identification
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 wide-range observation of the two-dimensional spatial distribution of absorption edge structures, similar to synchrotron radiation, without requiring thin samples or large devices.
Implementation Method 1
apply individual electron beams to an area on a sample which uses two different acceleration voltages to obtain an electron beam excitation characteristic X-ray spectrum
Implementation Method 2
With wavelength dispersive X-ray spectroscopy, a characteristic X-ray is dispersed through a diffraction grating, to thereby generate an intensity spectrum
Data Source
AI summary
An electron beam accelerated using a first acceleration voltage is applied to respective positions on a sample to obtain spectra A at the respective positions, and an electron beam accelerated using a second acceleration voltage different from the first acceleration voltage is applied to the respective positions on the sample to obtain spectra B at the respective positions. Then, a spectral ratio A/B of the spectra is calculated at each of the positions to generate a waveform representing the spectral ratio A/B. The value of a spectral ratio A/B in an energy region of interest is extracted from each of the waveforms. The extracted values are mapped onto points corresponding to the respective positions on the sample, whereby a spectral map is generated. The spectral map is displayed.