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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.


19F NMR spectrum for 34 and 130 nm-thick CaF2 thin films.Inset shows the peaks of 1H and 19F together. The linewidth of the 34 and 130 nm samples are 20 ± 6 G and 24 ± 6 G, respectively. Because the intrinsic linewidth of 19F NMR for CaF2 is approximately 10 G20, the thickness of the resonance slice is 200 nm in a magnetic field gradient of 50 G/μm. The image widths expected for the sample thicknesses of 34 and 130 nm are 1.7 and 6.5 G, respectively. The SNR of the 34 nm spectrum obtained after averaging 10 times is approximately 3.
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f4: 19F NMR spectrum for 34 and 130 nm-thick CaF2 thin films.Inset shows the peaks of 1H and 19F together. The linewidth of the 34 and 130 nm samples are 20 ± 6 G and 24 ± 6 G, respectively. Because the intrinsic linewidth of 19F NMR for CaF2 is approximately 10 G20, the thickness of the resonance slice is 200 nm in a magnetic field gradient of 50 G/μm. The image widths expected for the sample thicknesses of 34 and 130 nm are 1.7 and 6.5 G, respectively. The SNR of the 34 nm spectrum obtained after averaging 10 times is approximately 3.

Mentions: The 19F NMR spectra of 34 and 130 nm-thick CaF2 thin films obtained by our MRFM equipment are shown in Fig. 4. In fact, two peaks were detected that are separated by 4,590 G from each other (inset). The peaks on the left- and right-hand sites are the 1H and 19F NMR spectra, respectively. The difference in the gyromagnetic ratios of 1H, 42.6 MHz/T, and 19F, 40.1 MHz/T, is expected to produce 4,590 G at the resonance frequency of ω/2π = 313.3 MHz. Hydrogen gas appears to be adsorbed onto the thin film during or after the evaporation process. A similar observation was reported in earlier work19. It is useful to have the 1H spectrum together in the sense that it provides a reference for the exact field.


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)

19F NMR spectrum for 34 and 130 nm-thick CaF2 thin films.Inset shows the peaks of 1H and 19F together. The linewidth of the 34 and 130 nm samples are 20 ± 6 G and 24 ± 6 G, respectively. Because the intrinsic linewidth of 19F NMR for CaF2 is approximately 10 G20, the thickness of the resonance slice is 200 nm in a magnetic field gradient of 50 G/μm. The image widths expected for the sample thicknesses of 34 and 130 nm are 1.7 and 6.5 G, respectively. The SNR of the 34 nm spectrum obtained after averaging 10 times is approximately 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: 19F NMR spectrum for 34 and 130 nm-thick CaF2 thin films.Inset shows the peaks of 1H and 19F together. The linewidth of the 34 and 130 nm samples are 20 ± 6 G and 24 ± 6 G, respectively. Because the intrinsic linewidth of 19F NMR for CaF2 is approximately 10 G20, the thickness of the resonance slice is 200 nm in a magnetic field gradient of 50 G/μm. The image widths expected for the sample thicknesses of 34 and 130 nm are 1.7 and 6.5 G, respectively. The SNR of the 34 nm spectrum obtained after averaging 10 times is approximately 3.
Mentions: The 19F NMR spectra of 34 and 130 nm-thick CaF2 thin films obtained by our MRFM equipment are shown in Fig. 4. In fact, two peaks were detected that are separated by 4,590 G from each other (inset). The peaks on the left- and right-hand sites are the 1H and 19F NMR spectra, respectively. The difference in the gyromagnetic ratios of 1H, 42.6 MHz/T, and 19F, 40.1 MHz/T, is expected to produce 4,590 G at the resonance frequency of ω/2π = 313.3 MHz. Hydrogen gas appears to be adsorbed onto the thin film during or after the evaporation process. A similar observation was reported in earlier work19. It is useful to have the 1H spectrum together in the sense that it provides a reference for the exact field.

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.