Rural investment climate and business activities of agro-enterprise: Evidence from northern area of Vietnam

2013東京農業大

High-frequency pulsed ENDOR spectroscopy of the NV- centre in the commercial HPHT diamond

© 2015 Elsevier Inc. All rights reserved. This work reports direct 94 GHz ENDOR spectroscopy of the 14N nuclei in the NV- centre in single-crystal diamond. Roadmaps of ENDOR frequencies were measured and hyperfine/quadrupole interaction parameters were obtained, with AX,Y = -2.7 MHz, AZ = -2.2 MHz and P = -4.8 MHz. The sign and value of each parameter was calculated using spin Hamiltonian matrix diagonalization, first and second order perturbation theory and confirmed experimentally. Magnetic field magnitude was measured by 13C ENDOR signal with 0.02% precision or 0.5 mT. The orientation of quadrupole, hyperfine and fine structure tensors are the same within error of experiment, g-factor is isotropic

Size-dependent concentration of N0 paramagnetic centres in HPHT nanodiamonds

© Kazan Federal University (KFU). Size-calibrated commercial nanodiamonds synthesized by high-pressure high-temperature (HPHT) technique were studied by high-frequency W- and conventional X-band electron paramagnetic resonance (EPR) spectroscopy. The numbers of spins in the studied samples were estimated. The coreshell model of the HPHT nanodiamonds was proposed to explain the observed dependence of the concentration of the N0 paramagnetic centers. Two other observed paramagnetic centers are attributed to the two types of structures in the nanodiamond shell

Reply to 'Comment on "angstrom-scale probing of paramagnetic centers location in nanodiamonds by ³He NMR at low temperatures"' by A. Shames, V. Osipov and A. Panich,: Phys. Chem. Chem. Phys. 2018, 20, DOI: 10.1039/c8cp03331e

© the Owner Societies 2018. Shames et al. made a comment on our article (DOI: 10.1039/C7CP05898E) stating that their experience in EPR studies of detonation nanodiamonds suggests the existence of two main types of paramagnetic center in detonation nanodiamonds which questions our results. In this reply we provide insights into why there is only one main type of paramagnetic centers detected in nanodiamonds used in this work, which validates the correctness of the proposed original method to determine the distances between paramagnetic centers and nanoparticle surfaces by 3He NMR

Quantitative Analysis of Lewis Acid Centers of γ-Alumina by Using EPR of the Adsorbed Anthraquinone as a Probe Molecule: Comparison with the Pyridine, Carbon Monoxide IR, and TPD of Ammonia

© 2015 American Chemical Society. Quantitative electron paramagnetic resonance (EPR) measurements were done on the alumina oxide surface by using 9,10-anthraquinone probe (AQ) with the AQ amount in the range of (0.5-20) wt %. The nature of three paramagnetic centers observed simultaneously is ascribed to the strong, medium, and weak Al Lewis acid sites on the basis of combined EPR study/infrared (IR) spectroscopy of the adsorbed CO and pyridine/temperature-programmed desorption (TPD) of ammonia. It is shown how the optimal concentration of AQ probe molecule for the exhaustive quantitative examination of alumina surface can be determined directly from EPR. A possibility to characterize the surface distribution of Lewis acid centers by AQ molecules is discussed

Electron paramagnetic resonance in YbNiAl<inf>2</inf> single crystals with strong magnetic anisotropy

© 2017, Pleiades Publishing, Ltd.Anisotropy in the magnetic properties of YbNiAl2 intermetallide has been studied. Electron paramagnetic resonance (EPR) signals assigned to the localized magnetic moments of trivalent ytterbium have been detected at temperatures below 20 K. Spin–lattice relaxation processes like the Orbach–Aminov process with participation of the first excited Stark sublevel of the Yb3+ ion with an energy of 96 K govern electron–spin dynamics and the disappearance of spectrum lines with a further increase in temperature. Strong magnetic anisotropy effects are discussed as a main reason for the appearance of electron paramagnetic resonance

Electron paramagnetic resonance and electron nuclear double resonance study of the paramagnetic complexes of anthraquinone on the surface of γ-Al2O3

Progress in the synthesis and applications of nanomaterials including nanocatalysts demands a use of precise analytical tools for their surface characterization. Continuous wave (cw) and pulsed electron paramagnetic resonance (EPR) techniques, including electron-nuclear double resonance (ENDOR) have been applied to study paramagnetic complexes formed by adsorption of 9,10-anthraquinone (AQ) as probe molecule by the surface of γ-Al 2O3. Up to three different paramagnetic complexes (11-line pattern and two single EPR lines) could be separated in our experiments. Their spectroscopic characteristics are extracted. It is shown that at very high concentration (ca. 10 wt %) of AQ, the obtained EPR signal is close to the single line and can be incorrectly interpreted as due to the EPR signal of AQ itself or due to the lower catalytic activity of the investigated surface. That fact should be taken into account by using AQ as a probe of the surface catalytic activity. Mims and Davies ENDOR experiments confirm the redistribution of the electron spin density between the ring protons of AQ, aluminum nuclei in AQ-Al2O3 complexes, and remote proton and aluminum nuclei with AQ concentration. The corresponding electron-nuclear distances are extracted. The presented results can be used to expand the application of AQ as a sensitive probe for the catalysts surface characterization. © 2014 American Chemical Society