Method and system for magnetic resonance imaging using nitrogen-vacancy centers
A method for performing sub-nanometer three-dimensional magnetic resonance imaging of a sample under ambient conditions using a diamond having at least one shallowly planted nitrogen-vacancy (NV) center. A driving radio-frequency (RF) signal and a microwave signal are applied to provide independent control of the NV spin and the target dark spins. A magnetic-field gradient is applied to the sample with a scanning magnetic tip to provide a narrow spatial volume in which the target dark electronic spins are on resonance with the driving RF field. The sample is controllably scanned by moving the magnetic tip to systematically bring non-resonant target dark spins into resonance with RF signal. The dark spins are measured and mapped by detecting magnetic resonance of said nitrogen-vacancy center at each of said different magnetic tip positions. The dark-spin point-spread-function for imaging the dark spins is directly measured by the NV center.
1. A method for performing three-dimensional magnetic resonance imaging of a sample using a diamond having at least one shallowly planted nitrogen-vacancy center, wherein said diamond is in the focus of a confocal microscope, said imaging having sub-nanometer resolution on target dark electronic spins in said sample under ambient conditions, comprising the steps of:
applying a driving radio-frequency signal to said sample;
applying a microwave signal to said nitrogen-vacancy center;
applying a magnetic-field gradient to said sample with a scanning magnetic tip, wherein said magnetic field gradient provides a narrow spatial volume in which said dark electronic spins in said sample are on resonance with said driving radio-frequency field;
controllably scanning said sample by moving said magnetic tip to a plurality of different positions relative to said sample, thereby systematically bringing non-resonant target dark spins in said sample into resonance with said radio-frequency signal;
measuring said dark spins by detecting magnetic resonance of said nitrogen-vacancy center at each of said different magnetic tip positions.
2. The method for performing three-dimensional magnetic resonance imaging of a sample according to claim 1 , further comprising the step of generating a 3D mapping of a distribution of said dark electronic spins near said nitrogen-vacancy center, said 3D mapping having sub-nanometer resolution.
3. The method for performing three-dimensional magnetic resonance imaging of a sample according to claim 1 , further comprising the step of directly measuring a dark-spin point-spread-function for imaging said dark spins.
4. The method for performing three-dimensional magnetic resonance imaging of a sample according to claim 3 , wherein said step of directly measuring a point-spread function comprises the steps of:
simultaneously frequency-locking the applied microwave signal to a spin resonance of said nitrogen-vacancy center and measuring a magnetic tip-induced frequency detuning;
generating a spatial map of said magnetic tip-induced frequency detuning to determine a point-spread-function for imaging of said dark spins.
5. The method for performing three-dimensional magnetic resonance imaging of a sample according to claim 1 , wherein said step of applying a microwave signal to said nitrogen-vacancy center comprises executing a microwave spin-echo sequence on the nitrogen-vacancy center; wherein said microwave spin-echo sequence is synchronized with said radio-frequency signal.
6. The method for performing three-dimensional magnetic resonance imaging of a sample according to claim 1 , wherein the detected magnetic resonance at each said different tip position is made conditional on said applied driving radio-frequency signal by double electron-electron resonance.