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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.


Related in: MedlinePlus

Schematic drawing of MRFMs for imaging and spectroscopy.(a), MRFM setup for imaging. In an inhomogeneous field, only the nuclear spins experiencing the field satisfying the resonance condition are influenced upon the resonance condition. When the natural linewidth of the spectrum is Δω, the thickness of this resonance slice Δz is given as GΔz = Δω/γ where G is the field gradient. A small magnet generates a high gradient field and a thin resonance slice compared to the thickness of the sample. The resulting signal is the superposition of the sample image and the intrinsic spectrum. (b), MRFM spectroscopy setup. A large flat magnet generates a field homogeneous on the plane where the thin film sample is placed. The resonance slice contains the entire sample within it, thus minimizing the imaging effect on the spectrum.
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f2: Schematic drawing of MRFMs for imaging and spectroscopy.(a), MRFM setup for imaging. In an inhomogeneous field, only the nuclear spins experiencing the field satisfying the resonance condition are influenced upon the resonance condition. When the natural linewidth of the spectrum is Δω, the thickness of this resonance slice Δz is given as GΔz = Δω/γ where G is the field gradient. A small magnet generates a high gradient field and a thin resonance slice compared to the thickness of the sample. The resulting signal is the superposition of the sample image and the intrinsic spectrum. (b), MRFM spectroscopy setup. A large flat magnet generates a field homogeneous on the plane where the thin film sample is placed. The resonance slice contains the entire sample within it, thus minimizing the imaging effect on the spectrum.

Mentions: MRFM detects the force the sample magnetization experiences in the magnetic field gradient generated by the magnet. The smaller the magnet is, the stronger the gradient is and the higher the force and image resolution are. Therefore, a high field gradient is helpful both to enhance the force and the spatial resolution. In the imaging setup (Fig. 2a), a small magnet on the order of a nanometer generates a high gradient field. The resonance slice, where magnetic resonance occurs, is thin compared to the thickness of the sample. The resulting signal is the superposition of the sample image and the intrinsic spectrum.


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)

Schematic drawing of MRFMs for imaging and spectroscopy.(a), MRFM setup for imaging. In an inhomogeneous field, only the nuclear spins experiencing the field satisfying the resonance condition are influenced upon the resonance condition. When the natural linewidth of the spectrum is Δω, the thickness of this resonance slice Δz is given as GΔz = Δω/γ where G is the field gradient. A small magnet generates a high gradient field and a thin resonance slice compared to the thickness of the sample. The resulting signal is the superposition of the sample image and the intrinsic spectrum. (b), MRFM spectroscopy setup. A large flat magnet generates a field homogeneous on the plane where the thin film sample is placed. The resonance slice contains the entire sample within it, thus minimizing the imaging effect on the spectrum.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Schematic drawing of MRFMs for imaging and spectroscopy.(a), MRFM setup for imaging. In an inhomogeneous field, only the nuclear spins experiencing the field satisfying the resonance condition are influenced upon the resonance condition. When the natural linewidth of the spectrum is Δω, the thickness of this resonance slice Δz is given as GΔz = Δω/γ where G is the field gradient. A small magnet generates a high gradient field and a thin resonance slice compared to the thickness of the sample. The resulting signal is the superposition of the sample image and the intrinsic spectrum. (b), MRFM spectroscopy setup. A large flat magnet generates a field homogeneous on the plane where the thin film sample is placed. The resonance slice contains the entire sample within it, thus minimizing the imaging effect on the spectrum.
Mentions: MRFM detects the force the sample magnetization experiences in the magnetic field gradient generated by the magnet. The smaller the magnet is, the stronger the gradient is and the higher the force and image resolution are. Therefore, a high field gradient is helpful both to enhance the force and the spatial resolution. In the imaging setup (Fig. 2a), a small magnet on the order of a nanometer generates a high gradient field. The resonance slice, where magnetic resonance occurs, is thin compared to the thickness of the sample. The resulting signal is the superposition of the sample image and the intrinsic spectrum.

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.


Related in: MedlinePlus