Mesoscopic Fano effect modulated by Rashba spin-orbit coupling and external magnetic field

By employing non-equilibrium Green's function method, the mesoscopic Fano effect modulated by Rashba spin-orbit (SO) coupling and external magnetic field has been elucidated for electron transport through a hybrid system composed of a quantum dot (QD) and an Aharonov-Bohm (AB) ring. The results show that the orientation of the Fano line shape is modulated by the Rashba spin-orbit interaction k(R)L variation, which reveals that the Fano parameter q will be extended to a complex number, although the system maintains time-reversal symmetry (TRS) under the Rashba SO interaction. Furthermore, it is shown that the modulation of the external magnetic field, which is applied not only inside the frame, but also on the QD, leads to the Fano resonance split due to Zeeman effect, which indicates that the hybrid is an ideal candidate for the spin readout device. (C) 2007 Elsevier B.V All rights reserved.

The wave function evolution of an exciton in a bilayer system: Turning on a static in-plane electric field

The time evolution of the ground state wave function of an exciton in an ideal bilayer system is investigated within the framework of the effective-mass approximation. All of the moduli squared of the ground state wave functions evolve with time as cosine functions after an in-plane electric field is applied to the bilayer system. The variation amplitude and period of the modulus squared of the ground state wave function increase with the in-plane electric field F-r for a fixed in-plane relative coordinate r and fixed separation d between the electron and hole layers. Moreover, the variation amplitude and period of the modulus squared of the ground state wave function increase with the separation d for a fixed r and fixed in-plane electric field. Additionally, the modulus squared of the ground state wave function decreases as r increases at a given time t for fixed values of d and F-r. (c) 2007 American Institute of Physics.

on lin-bose problem

This paper study generalized Serre problem proposed by Lin and Bose in multidimensional system theory context [Multidimens. Systems and Signal Process. 10 (1999) 379; Linear Algebra Appl. 338 (2001) 125]. This problem is stated as follows. Let F ∈ Al×m be a full row rank matrix, and d be the greatest common divisor of all the l × l minors of F. Assume that the reduced minors of F generate the unit ideal, where A = K[x 1,...,xn] is the polynomial ring in n variables x 1,...,xn over any coefficient field K. Then there exist matrices G ∈ Al×l and F1 ∈ A l×m such that F = GF1 with det G = d and F 1 is a ZLP matrix. We provide an elementary proof to this problem, and treat non-full rank case.

Six-wave mixing phase-dispersion by optical heterodyne detection in dressed reverse N-type four-level system

We have investigated the dressed effects of non-degenerate four-wave mixing (NDFWM) and demonstrated a phase-sensitive method of studying the fifth-order nonlinear susceptibility due to atomic coherence in RN-type four-level system. In the presence of a strong coupling field, NDFWM spectrum exhibits Autler-Townes splitting, accompanied by either suppression or enhancement of the NDFWM signal, which is directly related to the competition between the absorption and dispersion contributions. The heterodyne-detected nonlinear absorption and dispersion of six-wave mixing signal in the RN-type system show that the hybrid radiation-matter detuning damping oscillation is in the THz range and can be controlled and modified through the colour-locked correlation of twin noisy fields.

Instabilities in a non-transferred direct current plasma torch operated at reduced pressure

Using an oscilloscope, a high-speed video camera and a double-electrostatic probe system, the periodicity and amplitude of the fluctuations in arc voltage, jet luminance and ion saturation current of a plasma jet were monitored to investigate various sources of instabilities and their effects in a non-transferred dc plasma torch operated at reduced pressure. The results show that besides a 300 Hz main fluctuation inherited from the power supply, arc voltage fluctuation of 3–4 kHz with an amplitude less than 5% of the mean voltage was mainly affected by the total gas flow rate. The arc voltage fluctuation can affect the energy distribution of the plasma jet which is detectable by electrostatic probes and a high-speed video camera. The steadiness of energy transfer is also affected by the laminar or turbulent flow state of the plasma.

Development of an intermediate energy heavy-ion micro-beam irradiation system

The micro-beam irradiation system, which focuses the beam down to micron order and precisely delivers a predefined number of ions to a predefined spot of micron order, is a powerful tool for radio-biology, radio-biomedicine and micromachining. The Institute of Modern Physics of Chinese Academy of Sciences is developing a heavy-ion microbeam irradiation system up to intermediate energy. Based on the intermediate and low energy beam provided by Heavy Ion Research Facility of Lanzhou, the micro-beam system takes the form of the magnetic focusing. The heavy-ion beam is conducted to the basement by a symmetrical achromatic system consisting of two vertical bending magnets and a quadrupole in between. Then a beam spot of micron order is formed by a magnetic triplet quadrupole of very high gradient. The sample can be irradiated either in vacuum or in the air. This system will be the first opening platform capable of providing heavy ion micro-beam, ranging from low (10MeV/u) to intermediate energy (100MeV/u), for irradiation experiment with positioning and counting accuracy. Target material may be biology cell, tissue or other non-biological materials. It will be a help for unveiling the essence of heavy-ion interaction with matter and also a new means for exploring the application of heavy-ion irradiation.

Photon emission from a chemically non-equilibrated parton gas at finite baryon density

We study hard photon production from a chemically non-equilibrated quark-gluon plasma with finite baryon density on the basis of Juttner distribution of partons of the system. We find that the photon production is ruled by early times, main contributions are given by rapidities y <= 6, and photon yield is a strongly increasing function of the initial quark chemical potential. In addition, we note that contribution from bremsstrahlung and Compton process qg -> q gamma dominates.

Non-reproducibility of the cross sections of the products induced from dissipative reaction of F-19+Al-27

The differential cross sections of the dissipative products B, Q N, O, F, Ne, Na and Mg induced from the reactions of F-19+Al-27 at two incident energies have been measured at the HI-13 tandem accelerator, Beijing. In the case of a fixed beam incident energy 114MeV or 118.75MeV respectively, identical reaction system and the same detection system, 20 target points in steps of 2mm on(.)a 10mmx50mm rectangular Al foil have been bombarded. The experimental results indicate that the probability distribution of the cross sections is much wider than a standard Gaussian distribution. This non-reproducibility of the cross sections can't be interpreted by the statistical property of a finite count rate.

Selective hydrogenation of unsaturated aldehydes in a poly(ethylene glycol)/compressed carbon dioxide biphasic system

Hydrogenation of alpha,beta-unsaturated aldehydes (citral, 3-methyl-2-butenal, cinnamaldehyde) has been studied with tetrakis(triphenylphosphine) ruthenium dihydride (H2Ru(TPP)(4)) catalyst in a poly(ethylene glycol) (PEG)/ compressed carbon dioxide biphasic system. The hydrogenation reaction was slow under PEG/ H-2 biphasic conditions at H-2 4 MPa in the absence of CO2. When the reaction mixture was pressurized by a non-reactant of CO2, however, the reaction was significantly accelerated.

Efficient preparation of silver nanoplates assisted by non-polar solvents

In the paper, we report an efficient method to prepare high yield (up to 97%) of silver nanoplates. Synthesis of silver nanoplates was carried Out in a binary solvent system of N,N-dimethylformamide (DMF) and toluene, in which DMF served as the reductant and polyvinylpyrrolidone (PVP) as the capping agent. By increasing the ratio of toluene to DMF to 7:6, silver nanoplates can be Successfully synthesized; otherwise other shaped nanoparticles would be the major products. The nanoplate sample was characterized by TEM, HRTEM, SAED, XRD, AFM and UV-visible spectroscopy, proving the high nanoplate purity of this sample. The influence of toluene content, other solvents, AgNO3 concentration, preparation temperature and chloride ions was also examined, which suggests that the function of nonpolar solvents in this system is to enhance the PVP coverage on silver surface and, furthermore, to facilitate the preferential adsorption of PVP on two (I I I) facets of silver nanoplates.

Facile, Efficient Copolymerization of Ethylene with Bicyclic, Non-Conjugated Dienes by Titanium Complexes Bearing Bis(beta-Enaminoketonato) Ligands

Copolymerizations of ethylene with 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene under the action of various titanium complexes bearing bis(beta-enaminoketonato) chelate ligands of the type, [(RN)-N-1=C(R-2)CH=C(R-3)O](2)TiCl2 (1, R-1=Ph, R-2=CF3, R-3=Ph; 2, R-1=C6H4F-p, R-2=CF3, R-3=Ph; 3, R-1=Ph, R-2=CF3, R-3=t-Bu; 4, R-1=C6H4F-p, R-2=CF3, R-3=t-Bu; 5, R-1=Ph, R-2=CH3, R-3=CF3; 6, R-1=C6H4F-p, R-2=CH3 R-3=CF3), have been shown to occur with the regioselective insertion of the endocyclic double bond of the monomer into the copolymer chain, leaving the exocyclic vinyl double bond as a pendant unsaturation. The ligand modification strongly affects the copolymerization behaviour. High catalytic activities and efficient co-monomer incorporation can be easily obtained by optimizing the catalyst structures and polymerization conditions.

Crystal structure and electrochemical properties of rare earth non-stoichiometric AB(5)-type alloy as negative electrode material in Ni-MH battery

The La0.85MgxNi4.5Co0.35Al0.15 (0.05less than or equal toxless than or equal to0.35) system compounds have been prepared by are melting method under Ar atmosphere. X-ray diffraction (XRD) analysis reveals that the as-prepared alloys have different lattice parameters and cell volumes. The electrochemical properties of these alloys have been studied through the charge-discharge recycle testing at different temperatures and discharge currents. It is found that the La0.85Mg0.25Ni4.5Co0.35Al0.(15) alloy electrode is capable of performing high-rate discharge. Moreover, it has very excellent electrochemical properties as negative electrode materials in Ni-MH battery at low temperature, even at -40degreesC.

The change of Eu3+-surroundings in the system Al2O3-B2O3 containing Eu3+ ions

The change of Eu3+-surroundings with the Al/B ratio varying from 4.5 to 2 and Eu/(Al + B) = 0.02, was investigated through X-ray diffraction, infrared spectra, excitation and emission spectra, and phonon sideband. The results show coexistence of the crystal phase Al18B4O33 and the amorphous phase and Eu3+ ions of the samples with the Al/B ratio from 3 to 2 are incorporated into the amorphous phase. It was also found that electron-phonon coupling strength decreases with the Al/B ratio from 3 to 2, non-radiative decay rate decreases, resulting in an increase of the Eu3+-emission intensity. (C) 1999 Elsevier Science Ltd. All rights reserved.