Study of the glow discharge in inert gases with water vapor

The behavior of the water vapor concentrations and fragments in wet plasma is studied. The results of plasma-chemical modeling are compared with the results of direct measurements of water molecule dissociation in plasma.     

Observation of light dragging in a rubidium vapor cell

We report on the experimental demonstration of the light dragging effect due to atomic motion in a rubidium vapor cell. We find that the minimum group velocity is achieved for light redshifted from the center of the atomic resonance and that the value of this shift increases with decreasing group velocity, in agreement with the theoretical predictions by Kocharovskaya, Rostovtsev, and Scully [Phys. Rev. Lett. 86, 628 (2001)].     

Simultaneous determination of the temperature and density of rubidium vapor

We propose a new method for the simultaneous determination of the temperature and atom number density in rubidium vapor. The method is based on the comparison of theoretical simulations of the self-broadened absorption profiles of rubidium resonance lines with the measured profiles. Absorption measurements performed in rubidium vapor indicate that in the spectral region around resonance lines (760–835 nm), excellent agreement between theoretical and experimental absorption profiles can be achieved. In the temperature interval 500–700 K, the simultaneous determination of the atom number density and temperature of rubidium vapor is possible. We have applied the present method to nearly homogeneous and inhomogeneous rubidium vapors generated in a sapphire cell. PACS 31.15.Gy; 32.30.Jc; 32.70.-n     

Emission characteristics of a glow discharge in a mixture of heavy inert gases with iodine vapor

The results of a systematic investigation of the emission characteristics of a low-pressure UV excimer-halogen lamp pumped by a longitudinal dc glow discharge are presented. The discharge was initiated in mixtures of heavy inert gases with iodine vapor at a total pressure of 100–2000 Pa and a power deposited into the plasma of 10–100 W. Current-voltage characteristics of the glow discharge and emission spectra of the plasma in the region of 190–360 nm are studied. The radiation intensity at the resonance line of the iodine atom (206.2 nm) and the intensity at the peaks of the XeI(B-X) (253 nm) and I₂(B-X) (342 nm) emission bands are analyzed as functions of the pressure and partial composition of the mixtures of Ar, Kr, and Xe with iodine vapor, as well as the electric power of the glow discharge. The most efficient gas mixtures are determined for an electric-discharge UV iodine vapor lamp with continuous-wave emission and a long service life before a change of the mixture is required.     

Compact diode-laser-pumped quantum light source based on four-wave mixing in hot rubidium vapor

Using a nondegenerate four-wave mixing process in hot rubidium vapor, we demonstrate a compact diode-laser-pumped system for the generation of intensity-difference squeezing down to 8?kHz with a maximum squeezing of -7?dB. To the best of our knowledge, this is the first demonstration of kilohertz-level intensity-difference squeezing using a semiconductor laser as the pump source. This scheme is of interest for experiments involving atomic ensembles, quantum communications, and precision measurements. The diode-laser-pumped system would extend the range of possible applications for squeezing due to its low cost, ease of operation, and ease of integration.     

铷原子蒸汽中的光偏振旋转效应

对铷原子(⁸⁷Rb)蒸汽中的法拉第旋转、光学偏振自旋转以及二者的叠加旋转效应进行了理论和实验研究.对三种情况下旋转现象建立了简单而有效的理论模型. 实验中把铷原子泡置于自行设计的磁屏蔽腔内, 以屏蔽地磁场的影响.实验选择⁸⁷Rb F=2→F'=3能级D2跃迁线并采用零多普勒光谱 实验结构消除多普勒展宽对实验光谱的影响. 实验中分别观测到了三种旋转现象,实验结果与理论模拟结果非常符合.     

Emission characteristics of a high-power glow discharge plasma in a mixture of inert gases with bromine and iodine vapor

The results of an investigation of the UV radiation from the plasma of a dc glow discharge in mixtures of inert gases with bromine and iodine molecules are presented. The current-voltage and spectral characteristics of a longitudinal glow discharge with a power of 10–250 W are studied. The power and the efficiency of the total UV radiation of the plasma, as well as the power of radiation at the spectral line of the iodine atom at 206.2 nm, are optimized as functions of the power deposited into the plasma and the composition of the gas mixture. In active media based on Kr-Br₂ mixtures, the molecular emission of the plasma was represented by bands at 207 (KrBr(B-X)) and 289 nm (Br ₂ ^* ), while, in He-Xe-I₂ mixtures, it was represented by bands at 253 (XeI(B-X)) and 342 nm (I₂).     

Melting of the condensed inert gases

The melting of a macroscopic system of bound atoms with a pairwise interaction is examined as a vacancy formation process. It is found that the existence of a liquid state is related to a double-humped dependence of the partition function on the number of vacancies, where the peaks correspond to the solid and liquid states and the heights of the peaks are equal at the melting point. In order for the liquid state to form, the derivative of the vacancy interaction with respect to energy must have a maximum. The vacancies are compressed as a result of the interaction. In the condensed inert gases, the specific energy of vacancy formation is proportional to the resulting empty space per atom. Zh. éksp. Teor. Fiz. 112, 1847–1862 (November 1997)     

Self-rotation of optical polarization in rubidium vapor

We present an experimental and theoretical study of self-rotation of optical polarization in a rubidium vapor.The atomic vapor is placed in a magnetic shielding cavity to suppress the Faraday rotation effect.In our experiment,Doppler-free spectroscopy configuration is used,and F = 2 → F ’ = 3 transition of 87Rb D2 line is chosen.We observe self-rotation of optical polarization effect at different pump light ellipticities.A theoretical analysis is then provided based on the experimental conditions.Theoretical simulation and experimental results are in good agreement.     

The tube character of electron drift in condensed inert gases

The behavior of an excess electron in condensed inert gases in an external electric field is considered at densities and temperatures at which the mobility of a slow electron is relatively high. On the basis of experimental data and a model of a pair electron interaction with atoms, an effective potential energy surface is constructed for an excess electron inside a dense inert gas. The region available for a slow electron consists of many intersecting channels that form a Delaunay network located between atoms. A drifting electron, as a quantum object, propagates along these channels (tubes), and electron transition between intersecting potential energy tubes of different directions provides an effective electron scattering. This mechanism of electron drift and scattering differs from that in gases and crystals. Peculiarities of electron drift inside dense inert gases are analyzed within the framework of this mechanism of electron scattering, leading to a moderate change of the electron mobility upon melting.     

Optical pumping of the Zeeman components in the rubidium vapor

We investigated the optical pumping of the Zeeman components of rubidium atoms, in the presence of the external magnetic field ranging from the geomagnetic up to 130 Gauss. Using the saturated absorption spectroscopy with linearly polarized pump and probe laser beams, the rubidium Doppler-free spectra at different magnetic field strengths were measured. The dips (negative intensity signals) in the saturated absorption spectra of the ⁸⁷Rb hyperfine transition lines were observed. They come as a result of the alignment process induced by the incoherent population transfer due to the hyperfine optical pumping. By inspection of the dips for different magnetic field strengths we were able to conclude about the dynamics of the alignment process in the external magnetic field. Present work is a part of the investigations concerning the influence of the magnetic field on the velocity selective optical pumping of the rubidium atoms induced by femtosecond frequency comb [D. Aumiler, T. Ban, H. Skenderovi?, G. Pichler, Phys. Rev. Lett. 95 (2005) 233001; T. Ban, D. Aumiler, H. Skenderovi?, G. Pichler, Phys. Rev. A 73 (2006) 043407].     

Nonexponential decay of spin polarization in rubidium vapor

Experimental data on the decay of spin polarization in rubidium vapor are compared with inferences of the theory developed by the authors for spin-polarized Boltzmann gases. It is demonstrated that the nonexponential pattern of polarization decay points to the anisotropy of the indicatrix of inelastic scattering of rubidium atoms at high temperatures. Estimates are obtained of the degree of anisotropy of such inelastic scattering, i.e., scattering with variation of total spin. Under the experimental conditions, the indicatrix of inelastic scattering turns out to be highly extended forward, with the degree of anisotropy of the order of 1000.     

钚气溶胶环境中惰性气体氪迁移过程研究

放射性气体的安全性问题是涉及反应堆运行中必需研究的重要问题.因此在钚气溶胶环境中,对钚材料裂变产生的放射性气体裂变产物,需要研究其在钚气溶胶环境中的迁移过程.对放射性惰性气体Kr87,Kr88的实验测量数据进行了具体分析.依据它们具有钚材料直接裂变和作为固体裂变产物子体两种来源这一物理特性,在不同的制样时间对Kr87/Kr88比值变化规律进行分析.确立了这两种来源的在钚气溶胶环境中的物理图像和迁移过程的物理模型,并与实验数据进行比较以验证模型的正确性. 关键词： 钚气溶胶 气体裂变产物 放射性Kr87/Kr88 迁移过程