NMR Spectrometer Magnetic Field Correction via Tilted Axis Shimming
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Solution Overview
Problem
Current methods for correcting static magnetic fields in NMR spectroscopy, especially in magic angle spinning (MAS) NMR, are inefficient and time-consuming, particularly when the sample is spun about an axis tilted from the static magnetic field, as they rely on one-axis gradient shimming which cannot effectively correct magnetic field homogeneity in solid-state NMR.
Innovation Solution
A nuclear magnetic resonance spectrometer that spins a sample about an axis tilted at a first angle with respect to the static magnetic field, using a control portion to determine and apply corrective magnetic field coefficients based on a distribution of the static magnetic field along the tilted axis, allowing for efficient correction of the magnetic field through a combination of first, second, and third-order magnetic field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one-axis gradient shimming is used to correct static magnetic field in MAS NMR, then the device complexity is reduced, but the magnetic field homogeneity cannot be effectively corrected
Solution Approach 1:
The patent transitions from one-axis gradient shimming to three-dimensional magnetic field mapping and correction. By measuring magnetic field distribution along three orthogonal axes (x, y, z) and applying corrective fields in all three dimensions, the system achieves comprehensive magnetic field homogeneity correction while maintaining reasonable device complexity through systematic measurement and correction procedures.
2Ease of operation
If traditional shimming methods are used without considering sample spinning axis orientation, then the adjustment process is simplified, but the correction effectiveness deteriorates
Solution Approach 1:
The patent introduces orientation-dependent parameters into the shimming process. By determining the spinning axis orientation and calculating orientation-dependent corrective field coefficients, the system adapts the shimming parameters to match the actual sample orientation. This ensures effective magnetic field correction regardless of the spinning axis orientation while maintaining systematic and reproducible adjustment procedures.
3Productivity
If magnetic field correction is performed without accounting for sample orientation, then the measurement process is faster, but the correction accuracy is insufficient
Solution Approach 1:
The patent performs preliminary measurement of the magnetic field distribution along three orthogonal axes before applying corrective fields. By first characterizing the magnetic field inhomogeneity through systematic measurement and then applying targeted corrections based on the measured distribution, the system achieves both speed and accuracy in the shimming process.
Solution Approach 2:
The patent implements a feedback mechanism where the magnetic field distribution is measured, corrective fields are applied based on the measured distribution, and the correction effectiveness is verified. This iterative feedback process ensures accurate magnetic field homogeneity correction while maintaining efficient measurement and correction procedures.
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 enables efficient correction of the static magnetic field applied to the sample, improving homogeneity and allowing for high-resolution NMR measurements by accurately determining and applying corrective magnetic field components, thus overcoming the limitations of existing methods.
Implementation Method 1
a static magnetic field generating portion for producing the static magnetic field in z direction
Implementation Method 2
a corrective magnetic field generating portion for producing a corrective magnetic field to correct the static magnetic field
Implementation Method 3
detecting a nuclear magnetic resonance signal emanating from the sample
Data Source
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AI summary
A nuclear magnetic resonance (NMR) spectrometer (100) and a method of magnetic field correction capable of correcting a magnetic field efficiently are offered. The spectrometer spins a sample (s) about an axis tilted at the magic angle, and has a corrective magnetic field generating portion (20) for producing a corrective magnetic field and a control portion (30) for controlling the operation of the corrective magnetic field generating portion (20). An arithmetic unit (34) included in the control portion (30) uses at least one of BZ(1), B1(1)e, and B1(1)o or the linear sum of at least two of them as the first-order magnetic field component of the corrective magnetic field, uses at least one of B2(2)e, B2(2)o, B2(1)e, and B2(1)o or the linear sum of at least two of them as the second-order magnetic field component of the corrective magnetic field, and uses at least one of BZ(3), B3(1)e, B3(1)o, B3(2)e, B3(2)o, B3(3)e, and B3(3)o or the linear sum of at least two of them as the third-order magnetic field component of the corrective magnetic field.