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1.
B.P.C. Rao† S. Ramaswamy† C. Gopalakrishnan N. Satya Vijayakumar K.R. Ganesh 《哲学杂志》2013,93(25):3463-3473
Two-dimensional carbon nanosheets have been fabricated using inductively coupled radio frequency plasma-enhanced chemical vapour deposition. The structural properties of the nanosheets have been characterised using atomic force microscopy, scanning electron microscopy and X-ray diffractometer. The magnetisation of the samples was studied using vibrating sample magnetometer. The magnetisation of the nanosheets was found to be diamagnetic for fast synthesis processes (30 and 60 min). On the other hand, the nanosheets exhibited a weak ferromagnetic response for the slow (120 min) synthesis process. Energy dispersive spectrometry and atomic absorption spectroscopy confirmed that the magnetisation exhibited by the carbon nanosheets was an intrinsic property and that it was not due to contamination from the substrate. Raman spectroscopy studies revealed that the ferromagnetic carbon nanosheets have a higher ratio (1.20) of graphite peak (I G) to disordered peak (I D) than normally expected (0.75–0.90). Available data indicated that the magnetisation was due to the presence of structural disorders. 相似文献
2.
Savukov IM Seltzer SJ Romalis MV 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,185(2):214-220
We demonstrate detection of proton NMR signals with a radio-frequency (rf) atomic magnetometer tuned to the NMR frequency of 62 kHz. High-frequency operation of the atomic magnetometer makes it relatively insensitive to ambient magnetic field noise. We obtain magnetic field sensitivity of 7 fT/Hz1/2 using only a thin aluminum shield. We also derive an expression for the fundamental sensitivity limit of a surface inductive pick-up coil as a function of frequency and find that an atomic rf magnetometer is intrinsically more sensitive than a coil of comparable size for frequencies below about 50 MHz. 相似文献
3.
Enhancement factor K0, which characterizes NMR and EPR frequency shifts for Cs-129Xe, is measured for the first time. The enhancement factor r-o was measured to be (702±41) at 80 ℃ and (653±20) at 90 ℃, using the NMR frequency shift, detected by atomic magnetometer at a low magnetic field of 100 nT. This result is useful for predicting the EPR frequency shifts for Cs and the NMR frequency shifts for 129Xe in spin-exchange cells. 相似文献
4.
Magnetic shielding property for cylinder with circular,square, and equilateral triangle holes 下载免费PDF全文
《中国物理 B》2021,30(6):60702-060702
The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_H), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole) S_H, the sequence of the shielding property is equilateral triangle square circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability. 相似文献
5.
We consider a four-level model for alkali metal atoms with optical pumping by nonresonant light under conditions when magnetic
dipole transitions are induced between energy sublevels of the hyperfine structure in the ground state. We present the dependences
of the observed signal as a function of the frequency detuning of the applied rf fields relative to the resonant value, calculated
in the density matrix formalism. We note the absence of a light shift in the radiofrequency-optical resonance signal, independent
of the amplitude of the rf field and the optical and thermal relaxation rates. We show that when using a modulation technique
for phase detection of the signal, its maximum discrimination ability is observed under conditions for simultaneous modulation
of the pump light intensity and the frequency of the rf field, which in principle does not occur in the classical two-level
model for optically oriented atoms in magnetic resonance.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 326–329, May–June, 2006. 相似文献
6.
介绍一种基于电磁感应原理和电子测量方法的低(工)频峰值磁强针,用以实现对居室内>10^-7T的磁干扰信号的检测。 相似文献
7.
Nurul Hidayah Abdullah Kamyar Shameli Ezzat Chan Abdullah Luqman Chuah Abdullah 《中国化学快报》2017,28(7):1590-1596
A facile and green synthetic approach for fabrication of starch-stabilized magnetite nanoparticles was implemented at moderate temperature. This synthesis involved the use of iron salts, potato starch,sodium hydroxide and deionized water as iron precursors, stabilizer, reducing agent and solvent respectively. The nanoparticles(NPs) were characterized by UV-vis, PXRD, HR-TEM, FESEM, EDX, VSM and FT-IR spectroscopy. The ultrasonic assisted co-precipitation technique provides well formation of highly distributed starch/Fe_3O_4-NPs. Based on UV–vis analysis, the sample showed the characteristic of surface plasmon resonance in the presence of Fe_3O_4-NPs. The PXRD pattern depicted the characteristic of the cubic lattice structure of Fe_3O_4-NPs. HR-TEM analysis showed the good dispersion of NPs with a mean diameter and standard deviation of 10.68 4.207 nm. The d spacing measured from the lattice images were found to be around 0.30 nm and 0.52 nm attributed to the Fe3O4 and starch, respectively. FESEM analysis confirmed the formation of spherical starch/Fe_3O_4-NPs with the emission of elements of C, O and Fe by EDX analysis. The magnetic properties illustrated by VSM analysis indicated that the as synthesized sample has a saturation magnetization and coercivity of 5.30 emu/g and 22.898 G respectively.Additionally, the FTIR analysis confirmed the binding of starch with Fe_3O_4-NPs. This method was cost effective, facile and eco-friendly alternative for preparation of NPs. 相似文献
8.
永磁体等效磁矩的测量 总被引:1,自引:0,他引:1
在磁技术应用中,对永磁材料的主要磁性参数的研究及测量已成为人们关注的问题之一.本文提出通过测量磁场从而确定永磁体磁矩的一种简便方法,并就测量所涉及的有关问题作了讨论. 相似文献
9.
K. Fuhrmann Th. Dries E. W. Fischer M. Ballauff 《Journal of Polymer Science.Polymer Physics》1992,30(11):1199-1206
A superconducting quantum interference device (SQUID) magnetometer suitable for measurements of the magnetic susceptibility up to 600 K has been used to follow the kinetics of realignment in the nematic phase of a side-chain liquid–crystal polymer. Experiments are performed using monodomain and polydomain samples. Results obtained in monodomain samples are in quantitative agreement with the prediction of the continuum theory up to an angle of approximately 60°. Experiments conducted at higher starting angles give clear indication of backflow effects. Data obtained from experiments on polydomain samples have been compared with model calculations using the data on the monodomain samples. This comparison leads to the conclusion that in this case backflow effects play an important role, too. All results show that SQUID magnetometry allows monitoring of the kinetics of realignment with highest precision. © 1992 John Wiley & Sons, Inc. 相似文献
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