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NMR spectroscopy for thin films by magnetic resonance force microscopy.

Won S, Saun SB, Lee S, Lee S, Kim K, Han Y - Sci Rep (2013)

Bottom Line: Nuclear magnetic resonance (NMR) is a fundamental research tool that is widely used in many fields.To minimize the amount of imaging information inevitably mixed into the signal when a gradient field is used, we adopted a large magnet with a flat end with a diameter of 336 μm that generates a homogeneous field on the sample plane and a field gradient in a direction perpendicular to the plane.Cyclic adiabatic inversion was used in conjunction with periodic phase inversion of the frequency shift to maximize the SNR.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea [2] Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831, Republic of Korea [3].

ABSTRACT
Nuclear magnetic resonance (NMR) is a fundamental research tool that is widely used in many fields. Despite its powerful applications, unfortunately the low sensitivity of conventional NMR makes it difficult to study thin film or nano-sized samples. In this work, we report the first NMR spectrum obtained from general thin films by using magnetic resonance force microscopy (MRFM). To minimize the amount of imaging information inevitably mixed into the signal when a gradient field is used, we adopted a large magnet with a flat end with a diameter of 336 μm that generates a homogeneous field on the sample plane and a field gradient in a direction perpendicular to the plane. Cyclic adiabatic inversion was used in conjunction with periodic phase inversion of the frequency shift to maximize the SNR. In this way, we obtained the (19)F NMR spectrum for a 34 nm-thick CaF2 thin film.

No MeSH data available.


Field profile generated by the magnet.(a), ESR spectra plotted as a function of the external magnetic field generated by a superconducting coil for various sample-magnet distances. The field generated by the magnet decreases as the sample-magnet distance increases. The external field generated by the superconducting coil increases to make the total field the same. (b), Field profile generated by a magnet with a diameter of 336 μm. In the NMR experiment, the sample was placed at a position 70 μm away from the magnet, where the field is relatively constant on the perpendicular plane.
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f3: Field profile generated by the magnet.(a), ESR spectra plotted as a function of the external magnetic field generated by a superconducting coil for various sample-magnet distances. The field generated by the magnet decreases as the sample-magnet distance increases. The external field generated by the superconducting coil increases to make the total field the same. (b), Field profile generated by a magnet with a diameter of 336 μm. In the NMR experiment, the sample was placed at a position 70 μm away from the magnet, where the field is relatively constant on the perpendicular plane.

Mentions: The ESR spectra obtained for various distances between the sample and the magnet are shown in Fig. 3a. The spectra were taken with the sample placed at the symmetry axis of the magnet. Since the field generated by the magnet decreases as the sample-magnet distance increases, the external field generated by the solenoid coil increases to make the total field the same. Repeating the experiment with the sample at the off-axial positions, we obtained the field profile shown in Fig. 3b. The figure shows that the equipotential surface is relatively flat near the center and bends approaching the edges as expected. In the NMR experiment, the sample was placed at a distance of 70 μm from the magnet, where the profile is flattest over a wide area. The field gradient of the magnet at this position was 50 G/μm when the total magnetic field was increased to 7.82 T using a superconducting coil for the NMR experiment.


NMR spectroscopy for thin films by magnetic resonance force microscopy.

Won S, Saun SB, Lee S, Lee S, Kim K, Han Y - Sci Rep (2013)

Field profile generated by the magnet.(a), ESR spectra plotted as a function of the external magnetic field generated by a superconducting coil for various sample-magnet distances. The field generated by the magnet decreases as the sample-magnet distance increases. The external field generated by the superconducting coil increases to make the total field the same. (b), Field profile generated by a magnet with a diameter of 336 μm. In the NMR experiment, the sample was placed at a position 70 μm away from the magnet, where the field is relatively constant on the perpendicular plane.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3824162&req=5

f3: Field profile generated by the magnet.(a), ESR spectra plotted as a function of the external magnetic field generated by a superconducting coil for various sample-magnet distances. The field generated by the magnet decreases as the sample-magnet distance increases. The external field generated by the superconducting coil increases to make the total field the same. (b), Field profile generated by a magnet with a diameter of 336 μm. In the NMR experiment, the sample was placed at a position 70 μm away from the magnet, where the field is relatively constant on the perpendicular plane.
Mentions: The ESR spectra obtained for various distances between the sample and the magnet are shown in Fig. 3a. The spectra were taken with the sample placed at the symmetry axis of the magnet. Since the field generated by the magnet decreases as the sample-magnet distance increases, the external field generated by the solenoid coil increases to make the total field the same. Repeating the experiment with the sample at the off-axial positions, we obtained the field profile shown in Fig. 3b. The figure shows that the equipotential surface is relatively flat near the center and bends approaching the edges as expected. In the NMR experiment, the sample was placed at a distance of 70 μm from the magnet, where the profile is flattest over a wide area. The field gradient of the magnet at this position was 50 G/μm when the total magnetic field was increased to 7.82 T using a superconducting coil for the NMR experiment.

Bottom Line: Nuclear magnetic resonance (NMR) is a fundamental research tool that is widely used in many fields.To minimize the amount of imaging information inevitably mixed into the signal when a gradient field is used, we adopted a large magnet with a flat end with a diameter of 336 μm that generates a homogeneous field on the sample plane and a field gradient in a direction perpendicular to the plane.Cyclic adiabatic inversion was used in conjunction with periodic phase inversion of the frequency shift to maximize the SNR.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea [2] Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831, Republic of Korea [3].

ABSTRACT
Nuclear magnetic resonance (NMR) is a fundamental research tool that is widely used in many fields. Despite its powerful applications, unfortunately the low sensitivity of conventional NMR makes it difficult to study thin film or nano-sized samples. In this work, we report the first NMR spectrum obtained from general thin films by using magnetic resonance force microscopy (MRFM). To minimize the amount of imaging information inevitably mixed into the signal when a gradient field is used, we adopted a large magnet with a flat end with a diameter of 336 μm that generates a homogeneous field on the sample plane and a field gradient in a direction perpendicular to the plane. Cyclic adiabatic inversion was used in conjunction with periodic phase inversion of the frequency shift to maximize the SNR. In this way, we obtained the (19)F NMR spectrum for a 34 nm-thick CaF2 thin film.

No MeSH data available.