钾原子中多种受激辐射参与的混频过程

当双原子共振激发钾原子于６Ｓ能级时,由光泵受激辐射和电离复合受激辐射参与的六波或四波混频,产生了位于紫外和紫区的诸多相干辐射、文中对多种混频机制进行了分析和讨论,并对所测得的相干辐射线进行了标识．     

Radiation Polarization Distribution Function of a Dye Laser

The Fokker–Planck equation for the distribution function of the intensity of an individual component has been solved in the approximation of the Ornstein–Uhlenbeck process within the framework of the formalism of the method of polarization components. Based on this solution, we have constructed the distribution functions of the degree of lasing radiation polarization, analyzed experimental data for a certain geometry of laser pumping, and determined the values of the distribution parameters, including the loss coefficients for the polarization component.     

Fluorescence of a Liquid Drop with a Dye Excited by Femtosecond Laser Pulses

Results of investigations into the spectral and power characteristics of two-photon fluorescence of a liquid drop with the Rhodamine 6G dye irradiated by femtosecond laser pulses are presented. It is demonstrated that stimulated emission of two types is realized in drops with the concentrated dye solution, namely, superfluorescence within the drop volume and lasing on whispering gallery modes.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 15–19, April, 2005.     

Hawking Radiation of Dirac Particles in a Variable-Mass Kerr Space-Time

The Hawking effect of Dirac particles in a variable-mass Kerr space-time is investigated by using a method called as the generalized tortoise coordinate transformation. The location and the temperature of the event horizon of the non-stationary Kerr black hole are derived. It is shown that the temperature and the shape of the event horizon depend not only on the time but also on the angle. However, the Fermi–Dirac spectrum displays a residual term which is absent from that of Bose–Einstein distribution.     

Effects of Inert Particles on Liquid Phase Hydrogenation Over Nano-sized Catalysts

The effects of inert particles on the liquid hydrogenation over nano-sized Ni–B catalysts were investigated in a batch reactor. Nitrobenzene hydrogenation was used as a test reaction. The effects of stirring speed and the dispersant/catalysts ratio were investigated. Addition of inert particle in the reaction system of nano-catalysts could increase the reaction conversion significantly. The reaction conversion increased with increasing stirring speeding until 900-rpm, and then decreased. The addition of inert particle to the reaction system could prevent the agglomeration of nano-metals and disperse them over the entire reaction system. Nano-metals were physically attached on the external surface of the inert particles. In addition, the addition of inert particle may enhance the absorption rate of hydrogen in solvent, and resulting in the increase of reaction rate. Both are beneficial to the reaction conversion. The enhancement effect of Al₂O₃ is much greater than that of SiO₂.     

染料荧光增强苯的受激拉曼散射

本文报道若丹明6G荧光增强苯的受激拉曼散射一阶Stokes谱线的实验研究,在若丹明6G苯溶液浓度为～10-3mg/ml时,获得了有效的增强,浓度为13×10-3mg/ml时最大增强因子达到32。对增强机制进行了物理解释。     

Hawking Radiation of Charged Particles from a Rotating Black String

Using Damour-Ruffini method, Hawking radiation of rotating black strings is studied. Under the condition that the total energy, total angular momentum and total charge are conservative, the transition probability from initial state (energy M+ω, charge Q+e and angular momentum J+m) to final state (energy M, charge Q and angular momentum J) for black strings is derived considering the reaction of radiation particles to spacetime. That is, the probability that black strings radiate particles with energy ω, charge e and angular momentum m is obtained. The real spectrum is not a strictly pure thermal spectrum. Our result is consistent with Parikh and Wilczek’s result. It satisfies the unitary principle of quantum mechanics. However, in our result there are not only the term that denotes effect of energy and charge of radiation particles but also the term that denotes effect of radiation particles angular momentum on rotating black strings angular momentum. We provide a new way for investigating radiation of black strings.     

On the Polarizability of a Cluster of Interacting Particles in Polarization Radiation

Physics of Atomic Nuclei - The study considers diffraction radiation, which is excited when an electron moves near a cluster of two interacting subwavelength particles. The interaction is...     

Anisotropy in Third-Order Nonlinear Optical Susceptibility of a Squarylium Dye in a Nematic Liquid Crystal

A squarylium dye is dissolved in 4-cyano-4＇-pentylbiphenyl （SCB） and oriented by sandwiching mixtures between two pieces of rubbed glass plates. The optical absorption spectra of the oriented squarylium dye-5CB layers exhibit high anisotropy. The third-order nonlinear optical responses and susceptibilities X^（3）e of squarylium dye in 5CB are measured with light polarizations parallel and perpendicular to the orientational direction by the resonant femtosecond degenerate four-wave mixing （DFWM） technique. Temporal profiles of the DFWM signal of the oriented squarylium dye-5CB layers with light polarizations parallel and perpendicular to the orientational direction are measured with a time resolution of 0.3ps （FWHM）, and are found to consist of two components, i.e., the coherent instantaneous nonlinear response and slow response due to the formation of excited molecules. A high anisotropic ratio of x^（3）e, 10.8 ：k 1.2, is observed for the oriented layers.     

Generation of High-Frequency Radiation in the Conditions of Superradiance of Particles with a Constant Dipole Moment

Journal of Experimental and Theoretical Physics - A localized ensemble of identical particles with a constant dipole moment generates during superradiance a coherent pulse of low-frequency...     

Hawking Radiation of Dirac Particles in a Nonuniformly Rectilinearly Accelerating Black Hole

The Hawking radiation of Dirac particles on the event horizon of a nonuniformly rectilinearly accelerating black hole is studied in this paper. First, we construct the symmetrized null tetrad from which the spin coefficients and Dirac equation are derived. Next, by proposing generalized tortoise coordinate transformation, the decoupling problem of the Dirac equation with nonzero rest mass is solved. Finally, by analytic continuation, the Hawking thermal spectrum formula of Dirac particle for nonuniformly rectilinearly accelerating black hole is obtained.     

The Structural Transitions in Liquid Crystals Doped with Fine Magnetic Particles

The stable ferronematics and ferrosmectics (combination of liquid crystals with fine magnetic particles) were prepared for 8CB liquid crystal and magnetc particles 11 nm in diameter. The structural transitions i.e. magnetic Fredericksz transition were indicated by means of dielectric and conductivity measurements.The experimental results i.e. the proof of initial condition ( is director of LC molecules and is magnetic moment of particles) and the increase of the threshold field of Fredericksz transition vs volume conduction of magnetic particles are in qualitative agreement with the Burylov and Raikher theory of thermotropic ferronematics.     

Liquid Flow in a Porous Channel with Electrokinetic Effects

In this paper, a fully developed laminar flow in a porous channel between two paralleled flat plates in the presence of a double layer electric field is analyzed. The linear Poisson-Boltzmann equation is suggested to model the double layer electric field near the solid-liquid interface. The equation of motion is extended by including the electrical body force generating from the double layer field and then solved analytically. Different from previous models, our proposed one is continuous in the whole flow field and matches commonly-accepted models in the field of fluid mechanics.Besides, the effects of various physical parameters such as the zeta potential, the electrokinetic separation distance, and the ratio of the streaming current to conduction current on the velocity, the pressure, the apparent viscosity of the fluid,as well as the streaming potential are discussed. Physical explanations on the changing trends of those physical quantities with various parameters are given.     

Energy Parameters and Spectral Characteristics of Lasing of a Liquid Dye Drop Incorporating Nanoparticles

The spectral characteristics and the energy parameters of the fluorescence of a liquid rhodamine-6G dye drop incorporating suspended TiO₂ nanoparticles are presented. It is demonstrated that the lasing threshold for modes of the whispering gallery of liquid dye drops is halved in the presence of nanoparticles.     

Tunneling Radiation of Vector Particles from a Quantum Correction Black Hole

The purpose of this paper is to discuss the Hawking radiation of vector particles from a quantum correction black hole by the mean of quantum tunneling. In order to achieve this purpose, based on the Proca field equation and WKB approximation, the quantum tunneling method is used to calculate the tunneling rate and Hawking temperature of the black hole. According to the analysis of the consequences, we find that the tunneling rate and Hawking temperature are related to the quantum parameter besides the horizon radius and mass of the black hole. Furthermore, when the results are compared with those of scalar particles and fermions of the black hole, no difference is found. Therefore, the tunneling rate and Hawing temperature of the black hole do not change with the type of radiation particles.

     

Hawking Radiation of Charged Particles in Reissner-NordstrSm Black Hole

We extend the method that Banerjee and Majhi have used to discuss Hawking radiation. Under the condition that the total energy and electrical charge of spacetime are conserved, we investigate Hawking radiation of the charged black hole by a new Tortoise coordinate transformation. Taking the reaction of the radiation of the particle to the spacetime into consideration, we not only derive the radiation spectrum that satisfies the unitary principle in quantum mechanics but also show that the contribution of ingoing particles is equal to the one of outgoing particles on the similar chemical potential term in radiation spectrum caused by charged particles.     

Saser (Sound Amplification by Stimulated Emission of Radiation)

A theoretical scheme of a saser (Sound Amplification by Stimulated Emission of Radiation) is proposed. A liquid with gas bubbles is used as the active medium. Pumping is performed with an alternating electric field or mechanical vibrations of the resonator. Phase bunching of initially incoherent radiators (bubbles) occurs under the action of acoustic radiation forces. The proposed scheme is similar to that of a free-electron laser. Two models of an active medium are studied. In the first model it is assumed that all bubbles have the same radius. In the second model a continuous distribution of bubble radii is studied. The starting values for sasers with square and cylindrical resonators are calculated. It is shown that in all cases studied these conditions are identical, to within a numerical factor. The operation of a saser in a nonlinear regime and the directional pattern of a saser in the saturation regime are studied. Zh. Tekh. Fiz. 67, 92–100 (April 1997)     

New Tortoise Coordinate and Hawking Radiation of Dirac Particles in a Non-stationary Kerr-Newman Black Hole

The Hawking effect of Dirac particles in a non-stationary Kerr-Newman black hole is investigated using an improved Damour-Ruffini method with a new tortoise coordinate transformation. In contrast with the old tortoise coordinate, the new one satisfies the dimensional requirement. It is interesting to note that the Hawking emission spectrum remains a blackbody one with a correction term ξ existing in the Hawking temperature. Compared with the old tortoise coordinate transformation, our results appears more accurate and reliable.