Probe for magnetic resonance force microscopy and method thereof

Patent metadata

Field	Value
Publication number	US-9678186-B2
Application number	US-201313755115-A
Country	US
Kind code	B2
Filing date	Jan 31, 2013
Priority date	Jan 30, 2012
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A probe for use in Magnetic Resonance Force Microscopy (MRFM) to provide an image of a sample comprising: a magnetic field source adapted to orient the spin of the nuclei in a sample; a detector capable of detecting a magnetic field comprising an oscillator; at least one conductor substantially surrounding the oscillator for forming a RF antenna for transmitting a radio frequency electromagnetic field; whereby the at least one conductor transmits a radio frequency electromagnetic field that influences the nuclei in the sample, and whereby the detector detects how the nuclei are influenced through the oscillations of the oscillator to provide identification information concerning the content of the sample. Also included is a method for magnetic resonance force microscopy of a sample.

First claim

The invention claimed is:

1. A probe for use in Magnetic Resonance Force Microscopy (MRFM) to provide an image or spectroscopy of a sample comprising:
a magnetic field source adapted to orient the spin of the nuclei in a sample;
a detector capable of detecting a magnetic field comprising an oscillator;
at least one conductor substantially surrounding the oscillator for forming a RF antenna for transmitting a radio frequency electromagnetic field;
whereby the at least one conductor transmits a radio frequency electromagnetic field that influences the nuclei in the sample, and whereby the detector detects how the nuclei are influenced through the oscillations of the oscillator to provide identification information concerning the content of the sample.

2. The probe of claim 1 wherein the oscillator is a longitudinal oscillator; and wherein the magnetic field source is a magnetic field generator; and wherein the plurality of conductors comprise at least two coils mounted on a silicon substrate having a hole therein to provide the longitudinal oscillator access to a sample's surface; and wherein the at least two coils are adapted to be connected to an RF source; and wherein the longitudinal oscillator operates to detect the change in the angle of the spin from the Zeeman axis of the sample's nuclei or electrons in response to the RF field.

3. The probe of claim 1 wherein the detector comprises a optical fiber adapted to transmit a laser beam; the oscillator comprises a magnetic particle and a reflecting surface which reflects light from a laser beam into the optical fiber to create an interferometer, and whereby the interferometer is used to determine the change in the cantilever's amplitude and/or frequency, which provides information on the angle of spin from the Zeeman axis of the sample's nuclei which provides information relating to the composition of the sample.

4. The probe of claim 1 wherein upon application of an RF pulse sequence to the at least one conductor, the magnetic moments of the sample's nuclei may be rotated so as to reverse the direction of the magnetic moments in the sample's nuclei, and whereby as the magnetic moments in the sample nuclei are rotated, the oscillator resonates at a measurable frequency which is correlated to the composition of the sample.

5. The probe of claim 1 wherein the at least one conductor comprise a series of coils each having first and second terminals which are adapted to be connected to a radio frequency generating source; whereby the sample's nuclei may be concurrently subjected to differing radio frequencies.

6. The probe of claim 1 wherein the at least one conductor is mounted on a substrate which surrounds the oscillator, the substrate having a hole therein for receiving the oscillator.

7. The probe of claim 6 wherein the at least one conductor is formed on the substrate in the form of a spiral having a plurality of turns.

8. A probe for scanning the surface of a sample using magnetic resonance force microscopy comprising:
a magnetic field source for producing a magnetic field;
a magnetic sensor comprising a magnetic particle and a support, the magnetic particle being operatively connected to the support;
an RF antenna at least partially surrounding the magnetic sensor for emitting an RF magnetic field across a portion of the sample; and
an optical sensor, positioned proximate the magnetic sensor, for detecting displacement of the support,
whereby the magnetic field from the magnetic field source operates to align the magnetic moments of the sample's nuclei and RF magnetic field operates to vary the alignment of the magnetic moments of the sample's nuclei, the magnetic sensor operating to respond to the variation in the alignments of the magnetic moments and displace the support, the optical sensor operating to sense the displacement of the support to thereby provide information as to the variance of the alignment of the sample's magnetic moments and thereby provide information as to the composition of the sample.

9. The probe of claim 8 wherein the RF antenna comprises a substantially closed loop of wire substantially surrounding the magnetic sensor.

10. The probe of claim 8 wherein the RF antenna comprises a plurality of loops surrounding the magnetic sensor.

11. The probe of claim 8 wherein the optical sensor is located between the RF antenna and the sample.

12. The probe of claim 8 wherein the support is a cantilever, and wherein the magnetic particle responds to the nuclei of the sample causing the cantilever's oscillation amplitude or frequency to change which provides information as to the identification of the sample's content and wherein the magnetic particle is one of a ferro-magnetic, paramagnetic, or superpara-magnetic particle.

13. A method for magnetic resonance force microscopy of a sample comprising:
providing a probe adapted to scan a surface of an arbitrarily sized sample, the probe comprising a support;
providing a magnetic sensor operatively associated with the support;
providing an RF antenna, at least partially surrounding the magnetic sensor, for emitting an RF magnetic field across at least a portion of the sample; the RF antenna adapted to be connected to an RF source for pulsing RF signals to the sample;
providing an optical sensor, positioned proximate to the magnetic sensor, for detecting displacement of the support element; the optical sensor comprising an interferometer for measuring displacement of the support;
providing a magnetic field source for generating a background magnetic field for the probe;
determining information concerning the sample by pulsing an RF field through the RF antenna and,
using the optical sensor, measuring the movement of the support.

14. The method of claim 13 wherein the RF antenna comprises at least one substantially closed loop of wire surrounding the magnetic sensor, and wherein the support comprises a reflective surface which reflects light from the optical sensor to form an interferometer, the interferometer's laser beams carry information that can be extracted to provide the composition of the sample.

15. The method of claim 14 wherein the RF antenna comprises a plurality of loops surrounding the magnetic sensor.

16. The method of claim 15 wherein the loops are one of irregularly shaped, polygonal, or substantially circular.

17. The method of claim 14 further comprising a display for displaying an image of the atomic level structure of the sample.

18. The method of claim 13 wherein the support element is adapted to be coupled to the sample.

19. The method of claim 13 wherein the support comprises silicon configured as a cantilever, and the magnetic sensor is a magnetic particle operatively associated with the cantilever, and wherein the optical sensor comprises a laser, and wherein laser interferometry tracks the motion of the cantilever which vibrates as magnetic spins of the nuclei or electrons of the sample interact with the magnetic particle, and wherein the cantilever is scanned in three dimensions and the cantilever vibrations produce a three-dimensional image of at least a portion of the sample.

Assignees

• Us Army

Inventors

• Alexson Dimitri Arthur
• Smith Doran Dakota

Classifications

• G01Q60/52

  Resonance · CPC title

• G01R33/323

  Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR · CPC title

• G01R33/34053

  Solenoid coils; Toroidal coils · CPC title

• G01N24/08 Primary

  by using nuclear magnetic resonance (G01N24/12 takes precedence) · CPC title

• G01R33/46 Primary

  NMR spectroscopy · CPC title