The kinetics of the (5 × 20) → (1 × 1) structural transition for Au(100)

The kinetics of the anion-induced (5 × 20) → (1 × 1) surface structural transition of reconstructed Au(100) electrodes was studied in sulfate-containing solutions by current transients. It is shown that lifting of the reconstruction follows a nucleation-and-growth type behavior which can be described by the Avrami equation. Moreover, for high positive potentials, i.e., high anion coverages, the current-transient analysis reveals instantaneous nucleation, whereas for low transition overpotentials and long transition times a mechanism with constant transition rate prevails. Apparent activation energies, which depend strongly on the electrode potential, are derived from the temperature dependence of the Avrami plots.     

平面旋转场诱导下磁流变液的结构模型

针对平面旋转场下磁流变液中诱导产生的层状结构 ,提出了恰当的理论模型 ,该模型成功的解释了层状结构在同步旋转状态下 :层间距随磁场的变化关系 ;旋转层的滞后角随旋转角频率以及其他物理量之间的关系 ;层半径与旋转角频率之间的关系 .理论结果与文献中发表的实验结果相吻合     

Rb(62D)原子与基态Rb原子,H2分子碰撞转移截面

本文用荧光法测量Rb(6²D)原子与基态Rb原子,H₂分子碰撞转移截面。结果表明:Rb(6²D)-Rb(5²s)转移截面为σ_fs=67×10^-14cm²,σ_tr=4.3×10^-14cm²,Rb(6²D)—H₂转移截面为σ_fs 关键词：     

自由电子激光振荡器的二维数值模拟

在柱二维坐标系中,用数值计算方法求解了摇摆器内电子模拟方程组、光场方程组和无源区(不含摇摆器区)经非自适应方法变换后的无源旁轴波动方程并设计了相应的程序R_2D。用该程序计算的数值结果表明,在有源条件下二维数值模拟结果与高斯光束近似下的数值模拟结果符合较好;取完全相同的计算条件R-2D程序与洛斯阿拉莫斯实验室(LANL)的FELEX程序的计算结果符合较好;初步认为LANL实验数据的物理图象合理,数值结果基本可信;最后给出北京自由电子激光器(BFEL)的一些物理数据。     

Application of microwave digestion to the preparation of sediment samples for arsenic speciation

Several extraction procedures are described allowing arsenic speciation in sediments. The extraction of organometallic compounds such as dimethylarsinic acid or monomethylarsonic acid is quite simple since these compounds are stable in the different extraction media (HCl/ HNO₃, H₃PO₄, ammonium oxalate) and are easily released independent of the extraction mode (magnetic stirring or microwave solubilization). Extraction yields are higher than 96% for these two arsenic forms. An HCl/HNO₃ microwave solubilization procedure allows the quantitative solubilization of mineral arsenic, but the differentiation between the two oxidation states is not possible owing to the oxidation of As(III) to As(V). Extractions with orthophosphoric acid or ammonium oxalate allow the solubilization of mineral arsenic with extraction yields ranging from 90 to 95% and the differentiation between As(III) and As(V). Nevertheless, the amount of As(III) is underestimated owing to its partial oxidation. The usefulness and advantages of microwave solubilization compared with conventional extraction procedures are discussed. Received: 17 May 1996 / Revised: 19 September 1996 / Accepted: 25 September 1996     

KrF准分子激光激发掺锗光纤折射率扰动的非线性过程

本文采用了一种简单的功率监测法,观察了KrF准分子激光对掺锗光纤折射率影响的非线性过程。观察到子纤芯折射率扰动过程中非稳定现象、饱和现象和折射率扰动的非线性。     

腔靶等离子体辐射温度空间分布测量

本文描述了用膜吸收法测量激光等离子体辐射温度空间分布的原理和方法给出了柱形缝靶轴向辐射温度随空间位置变化的特征,对测量结果进行了分析讨论。     

Adaptation of an echelle spectrograph to a large CCD detector

A broad range echelle spectrograph with a CCD matrix detector is developed for different applications in atomic spectroscopy. The compact optical design in combination with a dispersive entrance slit illumination offers a low stray light level and high throughput in the UV spectral region comparable only with spectrographs of higher focal length. Ray tracing calculations for typical wavelengths and the multi-line spectrum of an iron arc show the excellent overall spectrum quality. The subtraction of two partial spectra of different steel alloys demonstrates the spectra evaluation possibilities of the CCD spectrograph.     

Analysis and implementation of cross sync period underwater acoustical positioning techniques for underwater targets

I.IlltroductionWhenanactiveunderwateracousticalpositioningsystemissearchingforanunderwatertarget,itisnecessaryforittocompleteatransmittingandreceivingcycIewithineachworkingperiodinordertofindoutthelocationofthetargetcorrectly.Forexample,whenanunder-wateracoustica1synchronouspositioningsystemistrackinganunderwatertargetwithagivensynchr0nizingperiod,thepropagati0ntimeofthepositioningsignaltravellingfr0mthetaJrgettothearrayofthesystemshouldbelessthanthesynchronizingperiod0therwisetargetdis-tance…