共查询到20条相似文献,搜索用时 15 毫秒
1.
Blok H Disselhorst JA Orlinskii SB Schmidt J 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,166(1):92-99
An electron paramagnetic resonance (EPR) spectrometer is described which allows for continuous-wave and pulsed EPR experiments at 275 GHz (wavelength 1.1 mm). The related magnetic field of 9.9 T for g approximately 2 is supplied by a superconducting solenoid. The microwave bridge employs quasi-optical as well as conventional waveguide components. A cylindrical, single-mode cavity provides a high filling factor and a high sensitivity for EPR detection. Even with the available microwave power of 1 mW incident at the cavity a high microwave magnetic field B1 is obtained of about 0.1 mT which permits pi/2-pulses as short as 100 ns. The performance of the spectrometer is illustrated with the help of spectra taken with several samples. 相似文献
2.
Drescher M Kaplan N Dormann E 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2007,184(1):44-50
In analogy with Nuclear MRI, the ESR signal phase shift of conduction electrons moving in electrical currents along controlled magnetic field gradients can be used to generate spatial electronic current density maps. First two-dimensional images of the current density distribution in quasi-one-dimensional organic conductors are presented. 相似文献
3.
N. Suwuntanasarn W. D. Hutchison G. N. Milford R. Bramley 《Hyperfine Interactions》2007,180(1-3):25-28
An X-band pulsed electron spin resonance system has been designed and constructed specifically for studies of decoherence times of phosphorus donor electrons in silicon. The microwave electromagnetic field aspects of the structure have been analysed, and the probe head geometry optimised, through 3D electromagnetic simulations. Results for natural silicon samples at temperatures down to 6 K, are analysed and we obtain an estimate of the isolated spin decoherence time in natSi approximately an order of magnitude longer than previously measured. 相似文献
4.
C. von Borczyskowski J. Köhler W. E. Moerner M. Orrit J. Wrachtrup 《Applied magnetic resonance》2007,31(3-4):665-676
In 1993, two collaborations independently achieved the first optical detection of a single electron spin, using paramagnetic resonance of the triplet state of a single molecule. We review the context of this work and the main later results and give a brief outlook for future experiments based on the detection and manipulation of single spins by optical methods. 相似文献
5.
Ranjan Das Balu Venkataraman Vinod R Bhagat Ajit S Ghangrekar Thomas Kuruvilla B K Chaturvedi G S Isola B M Marwaha P G Nair R S Parolia B K Sarkar 《Pramana》1986,27(5):661-677
A computer-controlled X-band time domain electron paramagnetic resonance (EPR) spectrometer, with a time resolution of the
order of 0.5μsec, has been constructed with many of the crucial microwave components designed and fabricated by the Microwave Engineering
Group of TIFR. The spectrometer operates either in a microwave power pulsed mode for determination of spin-lattice relaxation
times by the saturation recovery technique or in the kinetic mode for determination of the time dependence of EPR signal after
laser excitation. It has an automatic frequency control, an automatic phase control and, most importantly, a field-frequency
lock which ensures good stability of the EPR line positions enabling signal averaging for extended periods. The constructional
details of the spectrometer and its performance in both the modes are described here by reporting results on certain typical
systems. 相似文献
6.
《Journal of Electrostatics》2014,72(3):222-227
The detection of free radicals such as hydroxyl radical and hydrogen radical for plasma in solution induced by a pulsed electrohydraulic discharge are successfully performed using electron spin resonance measurement. The plasma reactor is a barrier-type and consists of a stainless needle high-voltage (+35 to 65 kV) electrode partially immersed in the solution and a Pyrex glass solution container around which an aluminum film grounded electrode is wrapped. Streamers are induced in the solution. After adding iron (II) sulfate or radical trapping agent before the plasma application, the spectrum for radicals is clearly detected. A reactive dye solution is dramatically decolorized. 相似文献
7.
Laird EA Barthel C Rashba EI Marcus CM Hanson MP Gossard AC 《Physical review letters》2007,99(24):246601
An all-electrical spin resonance effect in a GaAs few-electron double quantum dot is investigated experimentally and theoretically. The magnetic field dependence and absence of associated Rabi oscillations are consistent with a novel hyperfine mechanism. The resonant frequency is sensitive to the instantaneous hyperfine effective field, and the effect can be used to detect and create sizable nuclear polarizations. A device incorporating a micromagnet exhibits a magnetic field difference between dots, allowing electrons in either dot to be addressed selectively. 相似文献
8.
An easy to assemble and inexpensive PC card that interfaces E-Line Varian spectrometers (E-6, E-9, E-12 and E-15) with IBM compatible PCs is presented. The card has a Programmable Interval Timer so it does not need an external clock making it instrument independent. The accessory contains its own RAM. This allows the device to store the spectrum while sampling is in progress, so the PC can meanwhile be used for any other task. 相似文献
9.
Strain-modulated electron spin resonance (SMESR) spectra of V2+ and Mn2+ centers in MgO are reported and the results are compared with those obtained for MgO : Cr3+. The SMESR line intensities show a characteristic angular dependence, proving that modulation of the off-diagonal elements of the -tensor is the predominant mechanism when a flexural mode of vibration is applied.For V2+ a small additional contribution due to modulation of the diagonal elements of is present. 相似文献
10.
H. Coufal 《Solid State Communications》1981,39(3):467-469
The ESR-signal of DPPH was recorded by detecting the modulation of the absorbed microwave power with a gas-coupled microphone. This photo-acoustic detection scheme is compared with conventional ESR-detection. Applications of the acoustical detection method to other modulation spectroscopic techniques, particularly NMR, are discussed. 相似文献
11.
A. N. Kozlova 《Russian Physics Journal》1966,9(1):78-79
The crossing point of the Cr+3 ion energy-levels in single-crystal K3Co(CN)6, with the applied magnetic field parallel to the y-axis, is determined experimentally. Precisely calculated values of the constants E and D of the EPR spin Hamiltonian are shown to agree closely with those obtained by other authors.In conclusion, I wish to thank Professor V. S. Grechishkin for supervising my work and discussing the results. 相似文献
12.
Blank A Dunnam CR Borbat PP Freed JH 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,165(1):116-127
NMR microscopy is routinely employed in fields of science such as biology, botany, and materials science to observe magnetic parameters and transport phenomena in small scale structures. Despite extensive efforts, the resolution of this method is limited (>10 microm for short acquisition times), and thus cannot answer many key questions in these fields. We show, through theoretical prediction and initial experiments, that ESR microscopy, although much less developed, can improve upon the resolution limits of NMR, and successfully undertake the 1 mum resolution challenge. Our theoretical predictions demonstrate that existing ESR technology, along with advanced imaging probe design (resonator and gradient coils), using solutions of narrow linewidth radicals (the trityl family), should yield 64 x 64 pixels 2D images (with z slice selection) with a resolution of 1 x 1 x 10 microm at approximately 60 GHz in less than 1h of acquisition. Our initial imaging results, conducted by CW ESR at X-band, support these theoretical predictions and already improve upon the previously reported state-of-the-art for 2D ESR image resolution achieving approximately 10 x 10 mum, in just several minutes of acquisition time. We analyze how future progress, which includes improved resonators, increased frequency of measurement, and advanced pulsed techniques, should achieve the goal of micron resolution. 相似文献
13.
We report on the observation of conduction electron spin resonance (CESR) in samples of specially purified magnesium. Measurements were made over the temperature range 4.2–300 K and at two frequencies, 9.27 and 21 GHz. It is found that in contrast with previous data, there is no upturn in the low temperature linewidth and little variation between samples. 相似文献
14.
A phenomenological model has been proposed for tunneling electron spin resonance (ESR) of an isolated surface spin situated in a scanning tunneling microscope (STM), which explains the dependence of features (local maxima) of the tunneling current on the radio-frequency (RF) electric field and on the position of the tip with respect to the spin. A crossover of the line shape of the resonance signals, whose nature in weak and strong pumping fields corresponds to Lorentzian and Fano resonances, respectively, has been interpreted. New ESR–STM effects that are linear and nonlinear in the RF field and are promising for developing the methods of controlling spin qubits have been predicted. 相似文献
15.
Kukushkin IV Smet JH Lyne Abergel DS Fal'ko VI Wegscheider W von Klitzing K 《Physical review letters》2006,96(12):126807
We have investigated the electron spin resonance at nonzero wave vector in GaAs single quantum wells by combining the virtues of high frequency surface acoustic wave generation to produce excitations with large wave numbers with a sensitive optical scheme to detect resonant absorption. The observed large deviations from the single particle Zeeman energy are attributed to the exchange interaction. The enhancement of the electronic g* factor is, however, substantially smaller compared with theoretical predictions for spin waves when adopting a bare Coulomb interaction potential. 相似文献
16.
《Journal of Magnetic Resonance (1969)》1976,21(2):285-293
A discussion is given of the possibility of applying autocorrelation techniques to the recording and analysis of electron spin resonance spectra showing first-order hyperfine structure. Procedures and computer program for the implementation of these possibilities are described and the anthracene cation is used as an illustrative example. 相似文献
17.
18.
A Nakamura D Paget C Hermann C Weisbuch G Lampel B.C Cavenett 《Solid State Communications》1979,30(7):411-414
We report the optical detection of electron spin resonance in p-type CdTe at 1.7 K in optical pumping conditions. The Overhauser shift of the electronic resonance, of the order of 45 G, is related to the sign of the electron g-factor g1. We measure . Using this g1 value and the previous results on the Knight shift, we deduce the value of the electron wavefunction on Cd in CdTe, which is consistent with the value in CdS. 相似文献
19.