• Journal of the Korean Magnetic Resonance Society
• /
• v.22 no.2
• /
• pp.34-39
• /
• 2018

The Nuclear Magnetic Resonance (NMR) technique using Dynamic Nuclear Polarization (DNP) procedures is one of the promising techniques that enable overcoming low sensitivity problems in NMR spectroscopy. We constructed an ODNP-NMR system using a commercial benchtop EPR spectrometer. The $^1H$ NMR peak area of water in aqueous solutions of 4-hydroxy-TEMPO was enhanced more than 95 times in the ODNP-NMR experiments. Our signal enhancement results were about 55% of the previously reported result. This could be due to non-uniform microwave power over a sample and unwanted sample heating by microwave. However, this portable ODNP-NMR spectrometer will be eventually useful for site-specific detection with nano-scale spatial resolutions and molecular dynamics studies with significantly improved signal sensitivity.

• Journal of the Korean Magnetic Resonance Society
• /
• v.24 no.2
• /
• pp.59-65
• /
• 2020

Nitrogen-Vacancy (NV) center in diamond has been an emerging versatile tool for quantum sensing applications. Amongst various applications, nano-scale nuclear magnetic resonance (NMR) using a single or ensemble NV centers has demonstrated promising results, opening possibility of a single molecule NMR for its chemical structural studies or multi-nuclear spin spectroscopy for quantum information science. However, there is a key challenge, which limited the spectral resolution of NMR detection using NV centers; the interrogation duration for NV-NMR detection technique has been limited by the NV sensor spin lifetime (T₁ ~ 3ms), which is orders of magnitude shorter than the coherence times of nuclear spins in bulk liquid samples (T₂ ~ 1s) or intrinsic ¹³C nuclear spins in diamond. Recent studies have shown that quantum memory technique or synchronized readout detection technique can further narrow down the spectral linewidth of NMR signal. In this short review paper, we overview basic concepts of nanoscale NMR using NV centers, and introduce further developments in high spectral resolution NV NMR studies.

• Journal of the Korean Magnetic Resonance Society
• /
• v.21 no.1
• /
• pp.1-6
• /
• 2017

Enhancements in NMR sensitivity have been the main driving force to extend the boundaries of NMR applications. Recently, techniques to shift the thermally populated nuclear spin states are employed to gain high NMR signals. Here, we introduce a technique called photochemically induced dynamic nuclear polarization (photo-CIDNP) and discuss its progresses in enhancing the solution-state NMR sensitivity.

• Journal of the Korean Magnetic Resonance Society
• /
• v.19 no.1
• /
• pp.29-35
• /
• 2015

The microscopic dynamics of $CsH_2PO_4$, with two distinct hydrogen bond lengths, are studied by static nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR. The proton dynamics of the two crystallographically inequivalent hydrogen sites were discussed in terms of the $^1H$ NMR and $^1H$ MAS NMR spectra. Although the hydrogen bonds have two inequivalent sites, H(1) and H(2), distinct proton dynamics for the two sites were not found. Further, the $^{133}Cs$ spectrum is more or less continuous near $T_{C1}$ (=153 K). Finally, the phase transition mechanism of $T_{C1}$ in $CsH_2PO_4$ is related to the ordering of protons.

• Journal of the Korean Magnetic Resonance Society
• /
• v.7 no.2
• /
• pp.80-88
• /
• 2003

We have performed $^{11}$ B nuclear magnetic resonance (NMR) measurements to microscopically investigate an electronic structure of the ferromagnetic state in three different compositions of calcium-hexaboride single crystals. Although the crystal structure of Ca $B_{6}$ is cubic and three NMR lines may be expected for the nuclear spin 3/2 of $_{11}$ B, a larger number of NMR resonance peaks have been observed. The frequency and intensity of those peaks distinctively changes depending on the angle between crystalline axis and magnetic field. Analyzing this behavior, we find that the electric field gradient(EFG) tensor at the boron has its principal axis perpendicular to the six cubic faces with a quadrupole resonance frequency $v_{Q}$ 600 kHz. Even though the magnetization data highlight the ferromagnetic hysteresis, $^{11}$ B NMR linewidth data show no clear microscopic evidence of the ferromagnetic state in three different compositions of Ca $B_{6}$ single crystals.s.

• Journal of Magnetics
• /
• v.22 no.1
• /
• pp.14-22
• /
• 2017

The NMR's probe consists of the static magnetic field generator (magnetic source) and the RF coil. It is very strict for the homogeneity of the static magnetic field intensity of the magnetic source, so the cost of the magnetic source is more expensive in the entire nuclear magnetic resonance instrument. The magnetic source generally consists of electromagnet, permanent magnet and superconducting magnet. The permanent magnet basically needs not to spend on operation and maintenance and its cost of manufacture is much cheaper than the superconducting magnet. Therefore, the permanent magnet may be the only choice for the static magnetic field device if we want to use the magnetic resonance instrument as an analyzer for production by reducing price. A new probe magnet was developed on the basis of the permanent magnet ring in this paper to provide a technological way for reducing the manufacturing cost, weight and volume of the existing nuclear magnetic resonance instrument (including MRI) probe.

• Journal of the Korean Magnetic Resonance Society
• /
• v.10 no.2
• /
• pp.197-202
• /
• 2006

[ $^{11}B$ ] nuclear magnetic resonance (NMR) measurements were performed on the single crystals of $TbB_4$ to investigate local electronic structure and 4f spin dynamics. $^{11}B$ NMR spectrum, Knight shift, spin-lattice and spin-spin relaxation rates were measured down to 4K at 8T. $^{11}B$ NMR shift and linewidth are huge and strongly temperature dependent due to the 4f moments. In addition, both are proportional to magnetic susceptibility, indicating that the hyperfine field at the boron site originates from the 4f spins of Tb. Below $T_N$, the single broad resonance peak of $^{11}B$ NMR splits into several peaks reflecting the local magnetic fields due to antiferromagnetic spin arrangements. The longitudinal and the transverse relaxation rates, $1/T_1\;and\;1/T_2$, independent of temperature above $T_N$, decreases tremendously confirming huge suppression of spin fluctuation below $T_N$.

• Journal of the Korean Magnetic Resonance Society
• /
• v.20 no.3
• /
• pp.82-86
• /
• 2016

Ginseng is used as a medicinal ingredient. The quality control of species, age, origin and manufacturing process is important. The metabolome of ginseng about quality was studied in many reports. Almost studies carried out the extract of ginseng, however, the reproducibility cannot be obtained using extracted sample. In this study, powdery ginseng samples were analyzed using high resolution-magic angle spinning nuclear magnetic resonance (HR-MAS NMR)-based metabolomics except extraction step. Sample was measured three times using 600 MHz NMR spectrometer equipped with nano probe. Reproducibility can be enhanced using this method and the metabolic profiles of ginseng were identified and quantified.

• Investigative Magnetic Resonance Imaging
• /
• v.12 no.2
• /
• pp.107-114
• /
• 2008

Purpose : The aim of this study is to determine possibility of application of in vivo proton ($^1H$) magnetic resonance spectroscopy (MRS) in distinguishing cystic mass arising around pancreas by comparison of in vivo MRS, in vitro MRS using 3T MR machine, based on nuclear magnetic resonance (NMR). Materials and Methods : We obtained spectra of in vivo MRS, in vitro MRS and NMR from abdominal mass arising around pancreas (mucinous cystic neoplasm=5, intraductal papillary mucin producing tumor=5, pseudocyst=1, and lymphangioma=1). We estimated existence of peak of in vivo MRS, and in vitro MRS concordant to that of NMR. We also evaluated differential peak for predicting specific disease. Results : Correlation of presence of peak with NMR showed showed sensitivity of 29.6%, specificity of 82.6% and accuracy of 67.7% on in vivo MRS (p = 0.096, McNemar test), sensitivity of 57.1% and specificity of 92.6% and accuracy of 82.3% on in vitro MRS (p = 0.362, McNemar test). The spectra of NMR for IPMT showed more frequent peaks at 3.5-4.0 ppm (p=0.026). Conclusion : Although chemical analysis, using NMR could be regarded as possible tool to differentiate cystic masses, in vivo and in vitro MRS need further technical evolution for clinical application.

• Journal of the Korean Magnetic Resonance Society
• /
• v.20 no.4
• /
• pp.109-113
• /
• 2016

Resonance frequencies from the $^{113}Cd$ and $^{133}Cs$ nuclear magnetic resonance (NMR) spectra for the $CsCdBr_3$ single crystal were measured at varying temperatures by the static NMR method. The temperature-dependent changes of these frequencies are related to the changing structural geometry of the ${CdBr_6}^{4-}$ units, which affects the environment of $^{133}Cs$. The spin-lattice relaxation rates ($1/T_1$) for the $^{113}Cd$ and $^{133}Cs$ nuclei were measured in order to obtain detailed information about the dynamics of $CsCdBr_3$ crystals. The dominant relaxation mechanisms for $^{113}Cd$ and $^{133}Cs$ nuclei are direct single-phonon and Raman spin-phonon processes, respectively.