Single-Crystal Sapphire Insert for In Situ Magic Angle Setting
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Solution Overview
Problem
Existing methods for setting the magic angle in solid-state nuclear magnetic resonance (SSNMR) measurements are prone to errors due to physical manipulations of the stator and rotor assembly, which can disturb the carefully set angle, leading to inaccuracies in the measurement.
Innovation Solution
Utilizing a single crystal sapphire cylinder insert aligned with the rotor's axis of symmetry, which allows for in situ adjustment and measurement of the angle relative to the magnetic field, eliminating the need for separate standard samples and reducing mechanical disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If physical manipulations of the stator and rotor assembly are used to set the magic angle, then the angle can be adjusted, but measurement precision deteriorates due to angle disturbance and inaccuracies
Solution Approach 1:
The patent replaces mechanical angle-setting methods with an optical detection system. A laser beam is directed through the rotor assembly, and the position of the laser spot on a detector is used to precisely determine and verify the magic angle orientation, eliminating mechanical disturbance and achieving sub-arcsecond precision.
Solution Approach 2:
The patent introduces a laser beam as an intermediary to transfer orientation information from the rotor assembly to a detector. The laser spot position serves as an intermediary indicator that allows precise measurement of the magic angle without direct mechanical manipulation of the stator or rotor.
2Measurement precision
If separate standard samples are used for angle setting, then angle verification is possible, but device complexity increases due to sample replacement procedures
Solution Approach 1:
The patent combines the angle verification function with the rotor assembly itself by incorporating an orientation indicator (such as a reflective surface or transparent marker) directly into the rotor structure. This eliminates the need for separate standard samples and allows angle verification to be performed in situ during normal operation.
Solution Approach 2:
The rotor assembly performs its own angle verification function through the integrated orientation indicator. The rotor's own structure (reflective surface, transparent marker, or geometric feature) serves as the reference for angle measurement, making the system self-verifying without requiring external standard samples or additional verification 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
Enables precise setting and verification of the magic angle with an accuracy of within a thousandth of a degree, ensuring high-resolution NMR spectra without the need for sample replacement, thus minimizing measurement errors.
Implementation Method 1
a technique known as magic angle spinning (MAS, though in this context 'spinning' refers to a reorientation rotation and not to nuclear quantum spin states) can be employed to average out anisotropic nuclear spin interactions by rapidly reorienting the sample about an axis inclined at 54.74° (the 'magic angle') with respect to the magnetic field
Implementation Method 2
Nuclear magnetic resonance studies magnetic nuclei by aligning them with an applied constant magnetic field (B0) in direction z and perturbing this alignment using an alternating magnetic field (B1) at radio frequencies (called RF pulses), orthogonal to z
Implementation Method 3
single crystal sapphire... due to their optical and microwave transparent properties
Implementation Method 4
single crystal sapphire... due to their optical and microwave transparent properties and thermal conductivity
Data Source
AI summary
An article includes a cylinder of single crystal sapphire for use during solid state nuclear magnetic resonance (SSNMR) measurements. The axis of the cylinder is aligned with an axis of symmetry of the single crystal. The cylinder is configured to rotate at a known angle and known fraction of an angular velocity as the sample during operation of the SSNMR system. In some uses, a current angle of a stator is determined based on separation of peaks in a measured signal from aluminum atoms in the sapphire crystal. Stator orientation is adjusted until the current angle is within a desired tolerance of a target angle, including one different from a magic angle.