Crystal Structure Analysis via Electron Diffraction and NMR
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Solution Overview
Problem
Current methods for analyzing crystal structures, such as monocrystalline X-ray diffraction, powder X-ray diffraction, monocrystalline neutron diffraction, electron diffraction, and solid-state NMR, face challenges in specifying structures of small crystals (≤1 µm), distinguishing elements with close atomic numbers, and observing hydrogen atoms due to size limitations, impurities, and low electron density.
Innovation Solution
A system combining electron diffraction and NMR measurement methods, with quantum chemical calculations, to specify both overall and local crystal structures by measuring diffraction patterns and NMR parameters, and optimizing the structure by attributing atom positions and bond information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If monocrystalline X-ray diffraction method is used, then crystal structure can be specified with good precision, but a large monocrystal (10-100 μm) is required which is not always available
Solution Approach 1:
The patent combines electron diffraction (providing overall structure information) with NMR measurement (providing local structure information including hydrogen atom positions) to achieve complete crystal structure specification without requiring large monocrystals. This merging of complementary techniques resolves the contradiction between measurement precision and crystal size requirements.
Solution Approach 2:
The patent divides the crystal structure analysis into two segments: overall structure determination by electron diffraction and local structure determination by NMR measurement. This segmentation allows each technique to operate on its optimal scale, with electron diffraction handling the global framework and NMR providing detailed local information, thereby eliminating the need for large monocrystals.
2Volume of moving object
If powder X-ray diffraction method is used, then microcrystal analysis is possible, but structure analysis requires many suppositions and may fail when impurities are present
Solution Approach 1:
The patent merges electron diffraction (giving reliable overall structure) with NMR measurement (giving reliable local structure and hydrogen positioning) to achieve impurity-resistant structure analysis. The complementary nature of these techniques allows cross-validation, improving reliability even when impurities are present, unlike powder X-ray diffraction which is highly sensitive to impurities.
3Measurement precision
If neutron diffraction method is used to observe hydrogen atoms, then hydrogen atom positions can be determined, but a further larger monocrystal is required and deuterium replacement is necessary
Solution Approach 1:
The patent substitutes the neutron diffraction method (requiring large crystals and deuterium replacement) with NMR measurement for determining hydrogen atom positions. NMR directly probes hydrogen nuclei without requiring large crystals or isotopic substitution, thereby resolving the contradiction between hydrogen detection capability and crystal size requirements.
4Volume of moving object
If electron diffraction is used alone, then overall structure can be measured, but local structure and hydrogen atom positions cannot be specified
Solution Approach 1:
The patent merges electron diffraction (providing overall structure) with NMR measurement (providing local structure and hydrogen information) to achieve complete structural information. This combination eliminates the information loss inherent in using electron diffraction alone, as NMR complements it with local atomic environment data and hydrogen atom positioning.
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 the specification of crystal structures for small crystals and those with impurities, distinguishing elements with close atomic numbers, and determining hydrogen atom positions, improving the accuracy and completeness of crystal structure analysis.
Implementation Method 1
an electron diffraction apparatus that measures an overall structure of a crystal of a specimen by electron diffraction
Implementation Method 2
an NMR apparatus that measures a local structure of the crystal by NMR measurement
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An electron diffraction apparatus measures an overall structure of a crystal of a specimen by electron diffraction. An NMR apparatus (14) measures a local structure of the crystal by NMR measurement. An analysis apparatus (16) combines the overall structure and the local structure to specify a structure of the crystal.