Influence of side electric potential on hysteresis loop parameters and electric permittivity in the Rochelle salt

It has been shown that the application of an electric potential to relatively narrow side electrodes of a thin perpendicular parallelepiped Rochelle salt sample plate leads to the disappearance of the hysteresis loop. The effect is permanent and can be observed after the side potential disconnection. Moreover, a reduction of both zero-field longitudinal permittivity maxima at the critical points is visible then. A non-zero remanent polarization and a non-zero coercive field are then able to be observed only at temperatures higher than that of the lower critical point and lower than that of the upper critical one. No corresponding temperature shift in reduced permittivity maxima has been noticed. A transition to below the lower critical point for the next few hours does not lead to restoration of the original properties formerly lost during the side potential application in the ferroelectric phase. Such restoration is possible by annealing the sample above the upper critical temperature.     

Acoustic vibrational resonance in a Rayleigh-Plesset bubble oscillator

The phenomenon of vibrational resonance (VR) has been investigated in a Rayleigh-Plesset oscillator for a gas bubble oscillating in an incompressible liquid while driven by a dual-frequency force consisting of high-frequency, amplitude-modulated, weak, acoustic waves. The complex equation of the Rayleigh-Plesset bubble oscillator model was expressed as the dynamics of a classical particle in a potential well of the Liénard type, thus allowing us to use both numerical and analytic approaches to investigate the occurrence of VR. We provide clear evidence that an acoustically-driven bubble oscillates in a time-dependent single or double-well potential whose properties are determined by the density of the liquid and its surface tension. We show both theoretically and numerically that, besides the VR effect facilitated by the variation of the parameters on which the high-frequency depends, amplitude modulation, the properties of the liquid in which the gas bubble oscillates contribute significantly to the occurrence of VR. In addition, we discuss the observation of multiple resonances and their origin for the double-well case, as well as their connection to the low frequency, weak, acoustic force field.     

The resonance peak in the high-Tc cuprates

I present a theory in which the resonance peak observed in inelastic neutron scattering experiments on YBa₂Cu₃O_6+x and Bi₂Sr₂CaCu₂O_8+x arises from a dispersing spin mode. I argue that it is heavily damped in the normal state and becomes visible in the superconducting state due to a drastic decrease in the spin damping. I show that a spin-fermion model correctly describes the doping dependence of the peak position and of its integrated intensity. Finally, I derive a criterion for the existence of the resonance peak in other cuprate superconductors.     

Bose gases near resonance: Renormalized interactions in a condensate

Bose gases at large scattering lengths or beyond the usual dilute limit for a long time have been one of the most challenging problems in many-body physics. In this article, we investigate the fundamental properties of a near-resonance Bose gas and illustrate that three-dimensional Bose gases become nearly fermionized near resonance when the chemical potential as a function of scattering lengths reaches a maximum and the atomic condensates lose metastability. The instability and accompanying maximum are shown to be a precursor of the sign change of g₂$g_2$, the renormalized two-body interaction between condensed atoms. g₂$g_2$ changes from effectively repulsive to attractive when approaching resonance from the molecular side, even though the scattering length is still positive. This occurs when dimers, under the influence of condensates, emerge at zero energy in the atomic gases at a finite positive scattering length. We carry out our studies of Bose gases via applying a self-consistent renormalization group equation which is further subject to a boundary condition. We also comment on the relation between the approach here and the diagrammatic calculation in an early article [D. Borzov, M.S. Mashayekhi, S. Zhang, J.-L. Song, F. Zhou, Phys. Rev. A 85 (2012) 023620].     

细胞色素bc_1复合物的共振拉曼光谱

对不同氧化还原状态的细胞色素 bc_1复合物的共振拉曼光谱进行了分析比较。对部分拉曼信号的变化进行了指认。细胞色素 c_1的还原引起1640cm~(_1)和1560cm~(_1)及1454cm~(_1)的明显变小,细胞色素 b 的还原引起1544cm~(_1)的下降。这些信号可以标志复合物中不同色素的氧化还原状态,对拉曼方法用于研究呼吸链酶系有重要参考价值。     

The influence of a magnetic field on the mosaic spread and growth rate of small Rochelle salt crystals

The growth rates of small (length <1 mm) crystals of Rochelle salt grown with and without a magnetic field have been measured at constant supersaturation (4%). It has been shown that some crystals grown in the presence of a magnetic field exhibit a decrease in the linear growth rate in the [010] direction relative to that shown under normal conditions. It was further noticed that a few crystals of the total number showed slight increases in growth rate. The fact that a majority of crystals showed a decrease in growth rate has given rise to speculations that this should be caused by an increase of strain (mosaic spread), resulting from a change of the mode of incorporation of the growth units into the crystal surface brought about by the applied magnetic field. The results show that most of crystals grown in the magnetic field have a higher mosaic spread and lower growth rate than observed during growth without an applied field. An increase in growth rate in the presence of the magnetic field, observed for a few crystals, might be explained by the relaxation of this strain by formation of dislocations, which in turn enhance the growth rate.     

激光脉冲延时方案对原子多步共振光致电离的影响

针对宁西京教授提出激光脉冲延时方案,在含时薛定谔方程理论框架下探讨了各种参数对激光共振电离效率的影响;并以镥原子共振电离为例,探讨了该方案用于激光共振电离质谱(LRIMS)同位素分析的可行性.结果表明:由于超精细结构能级激励拉比频率很难满足匹配条件,该方案很难用于宽带激光激励电离LRIMS同位素分析中.在理论分析基础上,给出了基于窄带激光激励电离的LRIMS同位素分析的光致电离方案.     

新型钍基熔盐堆多物理计算模型及分析

针对熔盐堆系统特点,提出了包含堆芯及其他主回路系统在内的多物理紧密耦合计算模型,并在此基础上自主开发了多物理分析程序TANG-MSR。利用该程序进行了新型钍基熔盐堆(TMSR)的设计,并对设计方案进行了稳态及瞬态分析。相关计算结果表明,TANG-MSR所采用的多物理模型能够很好地捕捉熔盐堆的主要物理现象,提出的新型熔盐堆设计在安全性和可持续性方面表现优异。关键词：多物理模型;新型钍基熔盐堆;稳态;瞬态 Abstract: Key words:     

Surface scattering resonance absorption of free electron in nano structured materials

A physical model has been established for calculating the electronic transportation in nano structured material when it is irradiated by a laser pulse with a power density in a magnitude of GW/cm². The Monte Carlo technique has been selected to deal with the electron scattering process. In the process of electrons absorbing laser energy, a surface scattering resonance absorption mechanism and a small-size effect can be found. The regularities of electron energy changes with laser wavelength, structure dimension, and orientation of nano-line have been analyzed.     

Piezoelectric resonance study of structural phase transitions in BaMnF4

Structural transitions of BaMnF₄ are studied by piezoelectric resonance. The results show that large structural modulations occur from 220 K to 250 K. It is found from the temperature-dependence of the resonance curves that successive phase transitions appear at about 226 K, 234 K and 244 K. The inconsistency of the transition temperature from a A2₁ am to an incommensurate phase is interpreted as intrinsic structural instability, but not by defects or impurities in the crystal of BaMnF₄ used.     

Optimal sideband-squeezing in the resonance fluorescence of a two-level atom

The quantum fluctuation spectra of phase quadratures of the fluorescent light from a coherently driven two-level atom damping in a common vacuum is investigated. We find that by optimally choosing the Rabi frequency of the driving field, detuning between the atom and the driving field, and phase of the local oscillator the strong sideband squeezing in the spectrum of the optimal phase quadrature can be created and the degree of squeezing in the sidebands can reach about 56%.     

Magnetic resonance investigations of LaCl 3 :Ce 3+ scintillators

In undoped and Ce 3+ -doped LaCl 3 EPR has been detected in the X-ray luminescence (XL-EPR) in K-band (25 v GHz) at 1.5 v K. Two excited triplet states with different EPR parameters and spectral shapes could be separated, both triplet states have been attributed to "out-of-plane" self-trapped excitons (STE) in LaCl 3 . No EPR signals of V K centres (self-trapped holes) could be detected in undoped or Ce 3+ -doped LaCl 3 after X-irradiation at low temperatures. X-irradiation of undoped LaCl 3 creates also an EPR spectrum which can be tentatively attributed to F-type defects. The scintillation mechanism is discussed.     

多孔介质中盐指现象的数值模拟

运用基于杂交网格的高精度数值方法研究了多孔介质中的盐指现象.该算法将基于边界拟合坐标下的高精度有限差分法和高精度的泊松方程快速求解器有效地结合在一起,从而达到提高整体的计算精度、计算效率和稳定性的目的.通过比较不同孔隙率的多孔介质对盐指对流的传热传质效应的影响,发现在标准孔隙率较低的多孔介质中,盐度扩散的速度明显比热扩散的速度快,盐指很快触及上下壁面,使得上下层的盐度梯度迅速减小,这是与非多孔介质具有明显差异之处. 关键词： 多孔介质 双扩散对流 盐指     

Quasioptical measurement of ferrite material parameters at terahertz frequencies by a new method: Faraday angle resonance

A new method for measuring the dielectric constant _r and the saturation magnetizationM _S of ferrites in the terahertz frequency region is introduced in theory and experiment. The method, which bases on a resonance effect of the Faraday angle, gives an estimation of the loss factor tan , too.The derivation of the effect is based on a simple 4-port model of the ferrite disc which is axially premagnetized.Using the scattering matrix from the 4-port model the resonance effect is described and the extraction of the material parameters of some special data from the measurement record is explained.The measurement setup at 290 GHz is described and records of the ferrite Trans Tech TT 1–105 are evaluated, including an error calculation. Data for the hard ferrite Philips Ferroxdure FXD 330 are given, too.Using error minimizing algorithms which fit the material parameters to the measurement data a further increase in accuracy can be achieved.     

真实体系光电离截面共振结构的理论研究

利用我们提出的普遍适用的精确光电离截面公式和介电影响函数研究了原子光电离共振结构受粒子数密度影响的效应.结果表明用新的光电离截面公式可以直接处理宏观环境对截面的影响,明显地优于孤立原子光电离截面公式.     

Structure elucidation of fluorescent H1 antihistamines by ultraviolet resonance Raman spectroscopy: solvent structures of tripelennamine and mepyramine

Ultraviolet Resonance Raman (UVRR) spectroscopy—a Raman technique that combines high sensitivity with high selectivity and does not suffer from background fluorescence—is applied to the fluorescent H₁ antihistamines tripelennamine (TRP) and mepyramine (MEP) in aqueous solution to elucidate their molecular structure as a function of pH. In a previous investigation of these compounds (C. Tardioli, G. Gooijer G. van der Zwan, J. Phys. Chem. B, 113 , (2009), 6949), the presence of gauche conformers caused by intramolecular interaction of the protonated alkylamine tail with the pyridine nitrogen was assumed to explain the pH dependence of the fluorescence properties. In order to validate this assumption, use is made of the resonant excitation of the aminopyridine chromophore in TRP and MEP. In that way, structural information associated with the vibrations of that moiety can be obtained, and the changes it undergoes upon protonation can be monitored. Assignment of the vibrations was achieved with the help of a number of other compounds, and quantum chemical calculations. N,N‐Dimethylaminopyridine (2DMP) and its mono‐protonated form (2DMPH⁺) were investigated, since this molecule was shown to have optical properties closely resembling those of the aminopyridine moiety in TRP and MEP. Assignment of the vibrations of 2DMP was accomplished by comparison with the resonance Raman spectra of two other reference structures, 2‐aminopyridine and dimethylaniline—for which ordinary Raman data are available—and by Gaussian calculations. UVRR spectra of TRP and MEP could be readily interpreted on the basis of vibrational assignments of the parent chromophores, i.e. 2DMP and 2DMPH⁺. Vibrations of the aminopyridine chromophore in TRP and MEP at neutral pH, where the aminoalkyl chain is protonated, are modified when compared to the vibrational pattern recorded for a fully neutral molecule in alkaline solution. This implies an electronic redistribution in the ring originating from internal hydrogen bonding between the aminoalkyl tail and the aminopyridine chromophore. Copyright © 2010 John Wiley & Sons, Ltd.     

On the nature of resonance splitting in coupled multiring optical resonators

The spectrum of resonance frequencies in so-called free-standing resonators, built with coupled ring or disk resonators is analytically and numerically investigated. The composite resonator which constitutes the core of numerous photonic devices such as channel dropping filters, dispersion compensators, laser mirrors, etc., determines the salient characteristics of the device, such as its passband width and free spectral range (FSR). The spectral characteristics of the resonances are determined by the refractive indices of the waveguides, the dimensions of the resonators, and the strength of coupling between them. Novel relationships between these parameters are described that result in the invariance of the splitting ratios and as a consequence maintain the passband characteristics of the associated devices. Waveguide attenuation affecting the Q factor of the composite resonators is found to have insignificant effect on their spectral characteristics.     

弯张换能器尺寸与其同相振动谐振频率的关系

本文用有限元计算方法研究了弯张换能器各方向尺寸与其同相振动谐振频率之间的关系，得出以下结论：不一定所有尺寸的换能器都具有理想的同相振动模态；长、宽、高尺寸不变时，若换能器的壳体厚度值增大，则同相振动的谐振频率值随之增大；壳体厚度不变的情况下，减小长，宽、高中的任意一个参数时，其同相振动谐振频率将增高。     

盐对DNA相变影响的非线性特性研究

在Prohofsky，Peyrard-Bishop等提出的描述DNA双螺旋分子结构模型以及实验测量的基础上 , 给出了与盐(指NaCl)浓度有关的哈密顿模型, 得到了非线性动力学方程及扭结孤波解.并 由此求出了DNA变性相变所需要的Peierls相变力. 进一步讨论了盐浓度对相界面和相变力的 影响, 得到的结果与实验测量一致. 关键词： DNA 盐浓度 相界面 相变力     

基于激光共振电离质谱的钆奇宇称高激发态研究

钆同位素可作为生产医用同位素¹⁶¹Tb等的靶材,受限于高效光电离路径缺失等问题,目前仅能通过电磁方法生产,为实现钆的多步光电离,需要获取高激发态等光谱数据.基于国内自主研发的高分辨激光共振电离质谱,利用双色三步光电离方案,扫描了钆的36900～37700 cm^-1能区,首次获取了7条奇宇称高激发态能级,能级位置准确度可达±0.1 cm^-1,并根据角动量选择定则确定了可能的J值,同时发现了可用于质谱性能检验的单色光电离谱线.