RF coil for magic angle spinning probe
AssigneeVarian, Inc.
InventorWai Ha Wong
Life of this patent
Estimating the term…
Abstract
A multimode RF probe for use with a sample oriented at an angle θ to a polarizing field B0 produces a resultant RF magnetic field exhibiting enhanced coupling to the sample. The multiple modes are furnished by a quadrature coil, or a solenoidal coil in combination with either a saddle coil or quadrature coil.
Claims16
An NMR probe for use with a polarizing magnetic field B0, comprising:
- a resonator having a cylindrical axis R, said axis R inclined at an angle θ to B0, said resonator sustaining a plurality of RF magnetic fields each comprising a distinct phase and direction, said resonator comprising an RF coil comprising two mutually isolated ports for maintaining two quadrature modes of said coil in operation, said modes each resonant at ω1.
- an RF source for exciting an RF magnetic field B1, said field B1 elliptically polarized in a plane orthogonal to said cylindrical axis R such that the projection of said elliptically polarized field onto a plane orthogonal to B0 is circularly polarized, and
- a sample retainer for holding an elongate sample along said cylindrical axis.
An NMR system comprising:
- a magnet for producing a polarizing field B0,
- an RF energy source,
- an RF receiver for detecting and resolving RF energy at selected frequency and phase, and
- an RF probe comprising a resonator having a cylindrical axis R, said axis R inclined at an angle θ to B0, said resonator sustaining a plurality of RF magnetic fields each comprising a distinct phase and direction, said RF magnetic fields comprising elliptically polarization in a plane orthogonal to said cylindrical axis R such that the projection of said elliptically polarized field onto a plane orthogonal to B0 is circularly polarized.
A method of establishing an RF magnetic field within an NMR probe of cylindrical symmetry comprising a symmetry axis, said RF magnetic field to exhibit a desired orientation with respect to another axis B0 inclined with respect to said symmetry axis, comprising the steps of:
- (a) energizing a first RF magnetic field amplitude A1 oriented along said symmetry axis at resonant frequency ω0, and phase ρ1, and
- (b) in substantial concurrence with step (a), energizing a second RF magnetic field amplitude A2 in a plane normal to said symmetry axis at resonant frequency ω0 and phase ρ2,
- (c) choosing a phase difference ρ2−ρ1, and said amplitudes A1 and A2 such that a circularly polarized wave is projected onto a plane orthogonal to B0.
A method of establishing a plane polarized RF magnetic field within an NMR probe of cylindrical symmetry comprising a symmetry axis, said symmetry axis to exhibit a desired orientation with respect to another axis B0 inclined with respect to said symmetry axis, comprising the steps of:
- (a) energizing a first RF magnetic field comprising vector amplitude A1 in a plane orthogonal to said symmetry axis, said first RF field comprising resonant frequency ω0, amplitude A1 and phase ρ1;
- and
- (b) in substantial concurrence with step (a), energizing a second RF magnetic field comprising vector amplitude A2 in said plane normal to said symmetry axis and orthogonal to said vector amplitude A1 said second RF magnetic field comprising resonant frequency ω0 and phase ρ1+π/2,
- (c) energizing a third RF magnetic field comprising vector amplitude A3 along said symmetry axis, said third RF magnetic field comprising resonant frequency ω0 and phase ρ3 in substantial concurrence with steps (a) and (b), wherein said amplitudes and phases are selected to produce a circularly polarized wave projected upon a plane orthogonal to B0.
Dependencies are inferred from the claim text.