共查询到19条相似文献,搜索用时 93 毫秒
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从积算符理论和实验上详细地研究了弱耦合双自旋体系(CHCl3的C-H双自旋体系)的Raman磁共振谱.对不同射频场强度及频偏的Raman谱进行了细致的理论和实验研究,表明积算符理论的计算与实验不仅在弱射频场而且在强射频场时都符合得相当好,克服了微扰论的局限,这为进一步研究复杂自旋体系的Raman谱提供了强有力的理论方法.研究还表明,小的射频频偏将有利于多量子跃迁信号的观测,而适当的射频场强则会提高多量子峰的强度
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当用微波场作用到V型三能级原子的两个激发态能级时,系统跃迁路径之间发生交叉耦合导致了量子相干效应.通过调节微波场的强度,可实现对原子吸收和色散性质的改变,并呈现零吸收高折射率现象.此外,微波场诱导的量子相干也可实现相对相位对探测光增益的控制. 相似文献
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当用微波场作用到V型三能级原子的两个激发态能级时,系统跃迁路径之间发生交叉耦合导致了量子相干效应.通过调节微波场的强度,可实现对原子吸收和色散性质的改变,并呈现零吸收高折射率现象.此外,微波场诱导的量子相干也可实现相对相位对探测光增益的控制. 相似文献
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Analytical expressions for multi-quantum signal generation of quadrupole nuclei have been derived. Combined with numerical simulation of the double rotor motion, a strategy is suggested for partial sideband suppression in multi-quantum NMR spectra. Synchronization of multi-quantum excitation and selective flip pulses with outer rotor motion increase outer rotor speed effectively two times. This is also demonstrated experimentally by triple–single quantum correlation spectra of 23Na and 67Rb. 相似文献
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Gschwind RM Kessler H Gemmecker G 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,137(1):285-288
A new multi-quantum version of the HBHA(CBCACO)NH experiment for partially deuterated protein samples is presented. The method is based on the significant reduction of the proton and carbon relaxation rates due to multi-quantum delays in highly deuterated proteins recently published by our group. The introduction of a multi-quantum period in the coherence transfer pathway of the HBHA(CBCACO)NH experiment yields a dramatic increase of sensitivity-on average 46% with a 75% deuterated sample of the homodimeric 31 kDa E. coli IIAMan domain. Additional resolution in the proton dimension can be achieved by a double time shared approach keeping the 1H single-quantum period at a minimum. 相似文献
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K. Tanaka K. Fujikawa M. Fujiwara N. Happo N. Kotera 《Optical and Quantum Electronics》2009,41(11-13):903-912
Nonparabolic band structure of InGaAs/InAlAs multi-quantum wells was studied theoretically and experimentally. The electron effective mass was derived even from eigen-states and this nonparabolicity was explicitly determined as a function of energy. Electron eigen-state energies applying Kane’s bulk band theory fitted very well with our experiments in the multi-quantum wells. 相似文献
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Effect of annealing on photoluminescence and microstructures of InGaN/GaN multi-quantum well with Mg-doped p-type GaN 总被引:3,自引:0,他引:3
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InGaN/GaN multi-quantum well structure with Mg-doped p-type GaN was grown by low-pressure metalorganic vapour phase epitaxy. After rapid-thermal-annealing at 700 and 900${^\circ}$C, both the red-shift and the blue-shift of the photoluminescence (PL) peak, the decreased and the enhancement of the PL intensity were observed. The transmission electron microscopic images showed that InGaN multi-quantum-dots-like (MQD-like) structures with dimensions less than 5$\tm$10nm were formed in InGaN wells. The changes of PL spectra could be tentatively attributed to the competition between the red-shift mechanism of the quantum-confined Stark effect and the blue-shift mechanism of the quantum size effect due to MQD-like structures. 相似文献
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I. A. Damaskin S. L. Pyshkin S. I. Radautsan V. E. Tazlavan 《Optical and Quantum Electronics》1973,5(5):405-410
A study has been made of photoconductivity in Cdln2S4 induced by 1.17 eV photons from a Q-switched neodymium laser. Both three-photon absorption, and two-photon absorption involving the emission of a phonon, have been investigated. The experimental data are in satisfactory agreement with the theory of multi-quantum transitions which takes into account the peculiarities of crystal zone structure.The investigation of competing multi-quantum transitions is a new method which permits one to obtain information on the fundamental optical constants of solids. 相似文献
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I. ?ifrea G. Pal M. Crisan 《Physica E: Low-dimensional Systems and Nanostructures》2011,43(10):1887-1895
We developed a set of equations to calculate the electronic Green's functions in a T-shaped multi-quantum dot system using the equation of motion method. We model the system using a generalized Anderson Hamiltonian which accounts for finite intradot on-site Coulomb interaction in all component dots as well as for the interdot electron tunneling between adjacent quantum dots. Our results are obtained within and beyond the Hartree–Fock approximation and provide a path to evaluate all the electronic correlations in the multi-quantum dot system in the Coulomb blockade regime. Both approximations provide information on the physical effects related to the finite intradot on-site Coulomb interaction. As a particular example for our generalized results, we considered the simplest T-shaped system consisting of two dots and proved that our approximation introduces important corrections in the detector and side dots Green's functions, and implicitly in the evaluation of the system's transport properties. The multi-quantum dot T-shaped setup may be of interest for the practical realization of qubit states in quantum dot systems. 相似文献
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Hwang DW Jhao WJ Hwang LP 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,172(2):214-221
In this study 2H T2rho DQF NMR spectra of water in MCM-41 were measured. The T2rho double-quantum filtered (DQF) NMR signal is generated by applying a radio frequency (RF) field for various durations and then observed after a monitor RF pulse. It was found that the transfer between different quantum coherences by the couplings during long-duration RF fields (i.e., soft pulses) and that residual quadrupolar interaction dominates the signal decay. Knowledge of coherence transfer during long-RF pulses has special significance for the development of sophisticated multi-quantum NMR experiments especially multi-quantum MRI applications. 相似文献
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Using a near-field scanning optical microscope, near-field photocurrent and topographic imaging has measured the effect on intrinsic electric fields and photocurrent propagation resulting from inserting multi-quantum barrier (MQB) super-lattices into quantum well lasers. Measurements on devices at two different excitation wavelengths have highlighted the sensitivity of the near-field optical technique. Strong correlations were seen in the photocurrent response of the multi-quantum barrier regions when compared with simulations made on the electric field generated within the structure. As a result, photocurrent attenuation was attributed to carrier confinement in these barrier regions when compared to a control sample. The measurements illustrate the effectiveness of the MQB, in addition to the sensitivity and power of the near-field photocurrent technique. 相似文献