Mechanical detection and imaging of magnetic resonance by magnetic moment modulation
AssigneeInternational Business Machines Corporation
InventorsDaniel Rugar, John A. Sidles, Costantino S. Yannoni
Life of this patent
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Abstract
Methods and apparatus for detecting (and, if desired, imaging) the effects of magnetic resonance in a spin-containing material by measuring the magnetic force acting on a mechanical cantilever having a low damping coefficient due to modulation of the magnetic moment of the material in the polarizing field direction at a frequency substantially lower than the spin resonance frequency. Modulation of the magnetic moment in the direction of the polarizing magnetic field may be achieved by modulating (i) the magnitude of the magnetic field in the polarizing direction or (ii) the frequency or amplitude of a high-frequency magnetic field.
Claims25
An apparatus for detecting magnetic resonance effects in a material containing magnetic spins having a spin resonance frequency, said apparatus comprising:
- means for polarizing the spins to create a magnetic moment in the direction of a polarizing magnetic field in the material;
- means for applying a high-frequency magnetic field to the material at a frequency substantially equal to the spin resonance frequency;
- means for creating a magnetic field gradient to which the material is subjected to exert a force between the material and field gradient creating means;
- a mechanical oscillator;
- the material and field gradient creating means being spaced in close proximity, with one of them being mounted on the oscillator;
- means for modulating the magnetic moment at a frequency .omega..sub.mod which is substantially lower than the spin resonance frequency to create a mechanical force that vibrates the oscillator at a frequency substantially lower than the spin resonance frequency;
- and
- means for detecting motion of the oscillator.
A method for detecting magnetic resonance in a material containing magnetic spins, said method comprising the steps of:
- providing a magnetic particle in close proximity to the material for subjecting the material to a magnetic field gradient for generating a magnetic force;
- mounting either the material or the magnetic particle on a mechanical oscillator;
- polarizing the spins in the material to create a magnetic moment in the material;
- applying to the material a high-frequency magnetic field substantially equal to a frequency .omega..sub.0 at which the spins resonate in the material;
- modulating the magnetic moment of the material at a frequency .omega..sub.mod which is substantially lower than the frequency .omega..sub.0 to create a mechanical force that acts on the oscillator and varies with a frequency substantially lower than the frequency .omega..sub.0 ;
- and
- detecting motion of the oscillator.
Dependencies are inferred from the claim text.