Sm3+在玻璃中的发光以及Sb6+、Ce6+、Gd3+对Sm3+发光性质的影响

本文研究了单掺(Sm3+,Ce3+、Gd3+.Sb3+、双掺(Sm3++Ce3+、Sm3++Gd3+,Sm3++Sb3+)和兰掺(Sm3++Gd3++Ce3+)约四十余种不同玻璃的发射谱和激发谱.探讨了玻璃成份和掺杂离子浓度对Sm3+发光性质的影响以及Ce3+,Gd3+、Sb3+、Ce3++Gd3+对Sm3+的敏化作用。     

有机阳离子对卤素钙钛矿太阳能电池性能的影响

采用第一性原理计算了CH_3NH_3PbI_3中有机部分CH_3NH_3~+和CH_3NH_3的静电特性.结果表明:CH_3NH_3~+具有强的亲电特性,CH_3NH_3的CH_3~-端具有弱亲电性,而NH_3~-端具有弱亲核性.发现在CH_3NH_3PbI_3中CH_3NH_3~+之间强静电排斥作用在相变中起着重要的作用,且在室温条件下CH_3NH_3~+在无机笼中具备活性和无序的特性,使得TiO_2/CH_3NH_3PbI_3异质结中n型TiO_2的电子通过界面扩散到CH_3NH_3PbI_3材料,并与CH_3NH_3~+结合形成CH_3NH_3,CH_3NH_3的静电特性导致在内建电场作用下更容易取向,取向的CH_3NH_3周围形成的静电场会变得更弱和更加均匀.这对无机框架上载流子的产生和传输更加有利,这样的异质结比传统的pn结具有更大优势.这是CH_3NH_3PbI_3太阳能电池高的光电转换效率的重要原因.     

1989年(第3卷)作者索引

二划至四划(丁、于、王)七划(杨、苟、苏、李、吴、何、 丁撒3(2)97.邱、邹、沈、张、陆、陈) T立叶3(l)25.杨光群3(2)165. 于万瑞3(2)43.杨宗庆3(3)250. 于鸿昌3(3)221,3(3)250.杨乾声3(4)298. 王惠3(2)165.杨景海3(3)198. 王一峰3(3)198.杨慕松3‘l)67. 王文魁3(3)211,3(4)257.苟清泉3(l)11.3(l)25. 王永国3(2)159.苏文辉3(l)42.3(3)198,3(3)250, 王光祖3(3)177.苏林祥3(l)1. 王汝菊3(2)152,3(2)156.李勇3(2)148. 王克钢3(3)18 1.李彬3(3)198, 王松涛3(3)20 3.李凤英3(2、152,3(2)156. 王金贵3(l)31.李伯助3气2)125. 王积方3(2)152,3(2)1…     

Yb3+敏化的Er3+/Ho3+共掺碲酸盐玻璃的上转换发光研究

用高温熔融法制备了系列Er3+/Yb3+共掺,Ho3+/Yb3+共掺,和Er3+/Yb3+/Ho3+三掺碲酸盐玻璃,在975 nm激光抽运下三种掺杂玻璃中都出现了较强的绿光和红光上转换.研究了Yb3+离子对Er3+和Ho3+离子上转换发光强度的影响以及Yb3+→Er3+,Yb3+→Ho3+能量传递效率.分析了碲酸盐玻璃中Yb3+直接敏化Er3+,Ho3+上转换发光机理.当Er3+和Ho3+浓度较低时,Er3+/Yb3+/Ho3+三掺玻璃的上转换强度随着Yb3+离子浓度的增加而增强,出现的548 nm绿光和660 nm红光主要是由于Er3+:4S3/2→4I15/2,Ho3+:5F4(5S2)→5I8和Er3+:4F9/2→4I15/2,Ho3+:5F5→5I8跃迁共同作用的结果.Er3+/Yb3+/Ho3+三掺碲酸盐玻璃的上转换机理受Er3+/Yb3+之间,Ho3+/Yb3+之间,Er3+/Ho3+之间三者共同相互作用影响,Er3+/Ho3+离子间存在的交叉弛豫过程可增加Ho3+离子在可见光范围的上转换强度.     

Energy levels and radiative lifetimes of 3pns 3P0 and 3pnd 3P0 series of Si I

The energy levels and lifetimes of 3pns ^3po （n = 7 - 35） and 3pnd ^3p0 （n = 6 - 17） series of neutral silicon are calculated and predicted by means of multichannel quantum defect theory （MQDT）. In addition, the perturbation caused by core-excited state 3s3p^3 is discussed. The 3pnd ^3p0 series, especially 3p4d ^3p0, 3p5d ^3P0, and 3p6d ^3P0 are perturbed strongly by the core-excited state 3s3p3 ^3P0. These cause the lifetime of 3pnd ^3P0 （n = 5 - 7） to be less than that of 3p4d 3Po. The lifetimes of 3p14d ^3P0 （65479.14 cm^-1） and 3p16d ^3p0 （65608.77 cm^-1） are less than that of their frontal states respectively, because these states are perturbed by 3p22s ^3p0 （65476.48 cm-1） and 3p30s ^3p0 （65608.99 cm^-1） respectively.     

GeⅩⅪ-SeⅩⅩⅢ离子n=3，△n=0跃迁谱线和振子强度的计算

用HFR方法对CaⅨ-KrⅩⅩⅤ离子3s^2，3s^3P，3s3d，3p^2组态能级结构进行了理论计算。在已有实验研究的基础上，通过分析离子能级沿等电子序列的变化规律，运用最小二乘拟合方法预言计算了GeⅩⅪ-SeⅩⅩⅢ离子3s^2，3s^3P，3s3d，3p^2组态14条精细结构能级值。在此基础上，进一步计算了GeⅩⅪ-SeⅩⅩⅢ离子3s^2-3s3p，3s3p-3s3d和3s3p-3p^2跃迁的23条谱线波长和相应的振子强度。计算结果与已有的实验值十分吻合，波长的最大不确定度为0．008nm。     

五磷酸铈晶体中Ln3+对Ce3+发光强度的影响

采用蒸发溶液法生长出一系列Ce0.9Ln0.1P5O14晶体。研究了晶体中Ln3+对Ce3+发光强度的影响。观察到,La3+,Lu3+和Y3+起稀释作用,使Ce3+的发光强度降低;加入一定量的Pr3+或Gd3+能使Ce3+的发光增强;Nd3+,Sm3+、Tb3+、Dy3+、Ho3+、Er3+或Tm3+等离子与Ce3+的能级有重叠,它们之间存在着竞争吸收或能量转移,从而使Ce3+的发光减弱。本文发现Eu3+和Yb3+对Ce3+有严重的猝灭作用。     

Sm~(3+)在玻璃中的发光以及Sb~(6+)、Ce~(6+)、Gd~(3+)对Sm~(3+)发光性质的影响

本文研究了单掺(Sm~(3+),Ce~(3+)、Gd~(3+).Sb~(3+)、双掺(Sm~(3+)+Ce~(3+)、Sm~(3+)+Gd~(3+),Sm~(3+)+Sb~(3+))和兰掺(Sm~(3+)+Gd~(3+)+Ce~(3+))约四十余种不同玻璃的发射谱和激发谱.探讨了玻璃成份和掺杂离子浓度对Sm~(3+)发光性质的影响以及Ce~(3+),Gd~(3+)、Sb~(3+)、Ce~(3+)+Gd~(3+)对Sm~(3+)的敏化作用。     

Yb3+/Ho3+/Tm3+共掺碲酸盐玻璃的上转换白光发射及其机理研究

采用高温熔融法分别制备了Yb3+/Ho3+,Yb3+/Tm3+和Yb3+/Ho3+/Tm3+共掺的碲酸盐玻璃。在980nm红外激光激发下,Yb3+/Ho3+/Tm3+共掺的玻璃样品显示了强的蓝光、绿光和红光发射,分别对应于Tm3+的1 G4→3 H6跃迁、Ho3+的5 F4(5 S2)→5I 8跃迁以及Ho3+的5 F5→5I 8和Tm3+的1 G4→3 F4跃迁。通过对比发现,Yb3+/Ho3+/Tm3+共掺样品中的红、绿光积分发射强度比值(3.95)明显大于Yb3+/Ho3+共掺样品(1.69),这是由于Ho3+和Tm3+间存在交叉弛豫过程3 H4(Tm3+)+5I 6(Ho3+)→3 F4(Tm3+)+5 F5(Ho3+)和3 F4(Tm3+)+5I 8(Ho3+)→3 H6(Tm3+)+5I 7(Ho3+)所致。在激发功率密度为8.2 W.cm-2时,Yb3+/Ho3+/Tm3+共掺样品的上转换发光色坐标值为x=0.345,y=0.338,非常接近于等能白光(x=0.333,y=0.333)。     

Enhancement of red emission by co-dopant Ln3+ ions in Eu3+ :LaOF nanoparticles

Fluoride nanoparticles of Ln3+(Ln3+=Pr3+,Nd3+,Sm3+,Gd3+,Tb3+Dy3+,Ho3+,Er3+,Tm3+,Yb3+)/Eu3+:LaOF and Eu3+ :LaOF with rhombohedral crystal structure were prepared by a hydrothermal-sintering method. The red fluorescence emission of Eu3+ ions was found to be enhanced with most of the co-dopant Ln3+ ions. Compared with strong fluorescence emission at 610 nm of Eu3+ :LaOF nanoparticles, the enhancement factors was up to ten times in Ln3+(Ln3+ =Gd3+,Dy3+,Tm3+)/Eu3+ :LaOF co-doped nanoparticles. The results show that the asymmetry of the local environment of Eu3+ ion was reduced by co-doping Ln3+ ion into the nanoparticles, and that energy transfer might occur between Eu3+ and codopant Ln3+ ions, which is suggested as the source of the observed fluorescence enhancement.     

Simplified setup for high-resolution spectroscopy that uses ultrashort pulses

Using a broadband femtosecond laser and a simple optical setup, we demonstrate narrow-bandwidth-tunable excitation of vibrational modes in CCl4 and CHBr3 liquids. The resolution obtained is 80 times higher than the laser bandwidth. A pair of time-shifted, linearly chirped pulses is created by use of a high-order dispersion-compensated prism-interferometer setup. We use this pulse pair to selectively excite Raman-active transitions. Our setup represents a significant simplification with improved resolution, of previous approaches to the use of ultrashort pulses for chemically selective spectroscopy.     

Substituent effect on electron affinity,gas‐phase basicity,and structure of monosubstituted propargyl radicals and their anions: a theoretical study

The substituent effect of electron‐withdrawing groups on electron affinity and gas‐phase basicity has been investigated for substituted propargyl radicals and their corresponding anions. It is shown that when a hydrogen of the α‐CH₂ group or acetylenic CH in the propargyl system is substituted by an electron‐withdrawing substituent, electron affinity increases, whereas gas‐phase basicity decreases. The calculated electron affinities are 0.95 eV (CH?C? CH₂?), 1.15 eV (CH?C? CHF?), 1.38 eV (CH?C? CHCl?), 1.48 eV (CH?C? CHBr?) for the isomers with terminal CH and 1.66 eV (CF?C? CH₂?), 1.70 eV (CCl?C? CH₂?), 1.86 eV (CBr?C? CH₂?) for the isomers with terminal CX at B3LYP level. The calculated gas‐phase basicities for their anions are 378.4 kcal/mol (CH?C? CH₂:^?), 371.6 kcal/mol (CH?C? CHF:^?), 365.1 kcal/mol (CH?C? CHCl:^?), 363.5 kcal/mol (CH?C? CHBr:^?) for the isomers with terminal CH and 362.6 kcal/mol (CF?C? CH₂:^?), 360.4 kcal/mol (CCl?C? CH₂:^?), 356.3 kcal/mol (CBr?C? CH₂:^?) for the isomers with terminal CX at B3LYP level. It is concluded that the larger the magnitude of electron‐withdrawing, the greater is the electron affinity of radical and the smaller is the gas‐phase basicity of its anion. This tendency of the electron affinities and gas‐phase bacisities is greater in isomers with the terminal CX than isomers with the terminal CH. Copyright © 2009 John Wiley & Sons, Ltd.     

色氨酸与消毒剂反应形成三卤甲烷的光谱分析

使用荧光光谱和紫外光谱分析消毒剂(自由氯,自由溴)和色氨酸的反应及消毒副产物三卤甲烷的产生特性。实验表明：消毒剂反应降低了色氨酸荧光强度和FRI值(fluorescence region integration),二者线性相关。消毒剂中自由溴比例增加,荧光团FRI降低,UV₂₈₀值降低,UV₂₅₄值增加。THMs中溴代产物比例也随自由溴比例单调增加,而THMs总量没有呈现相似的变化规律。反映出和自由氯相比,自由溴取代性更强而氧化性更弱。自由溴单独和色氨酸反应时,FRI与CHBr₃产生量线性相关。加入NH₃后,消毒剂性质改变使得线性被破坏。     

Formation of a ripple pattern at a water/silicon interface using an oscillating bubble

A single femtosecond laser pulse was irradiated at a water/silicon interface, and the processed surface was investigated. Rings surrounded by ripples were found within the irradiated spot. The diameter of the rings ranged from 500 nm to 10 μm. It is proposed that acoustic waves, caused by the oscillating motion of bubbles near the water/silicon interface, deformed the melting silicon surface. In the present work, a pulse (pulse width: 150 fs) was tightly focused in water to induce optical breakdown, and a bubble was generated at an arbitrary spot. When the power density was below the ablation threshold and above the melting threshold at the silicon surface and set above the breakdown threshold at the focus in water, a pattern was generated at a specific place and with a specific size. PACS 79.20.Ds; 42.62.Cf     

Nitrate degradation without 15N enrichment: a hydrochemical and isotopic study of a fractured rock aquifer including embedded lakes

Water samples from three quarry lakes and the surrounding fractured rock aquifer were investigated for delta18O and delta2H (H2O), delta15N and delta18O (NO3-), as well as anions and cations. Lake water and groundwater can be distinguished by their different chemical and isotopic composition. Because of evaporation processes, 18O and 2H are enriched in the lake water and can be used as natural tracers for the water dynamic of the lakes. The groundwater is characterised by high nitrate concentrations (up to 120 mg/l). Lake internal processes reduce the nitrate concentration in the quarry lakes. However, no enrichment of delta15N and delta18O in nitrate, typical for microbial nitrate degradation, is observed in the lake water. Because of the complex flow paths in the fractured rock aquifer and the intense chemical transformations at the interface between groundwater and lake water, isotopic and hydrochemical data of lake water and groundwater alone do not conclusively explain hydrological and hydrochemical processes of the investigated lake-groundwater system.     

Water entry of a superhydrophobic low-density sphere

Abstract  

This paper virtually demonstrates an air cavity formed by a superhydrophobic low-density sphere entering into water with the use of a high-speed camera. Unlike the previous results for a high-density sphere, the low-density sphere pinches off the resulting air cavity at the shorter depth before the cavity has fully grown, and attracts minimal air on the rear surface due to rapid deceleration of the sphere in water. The analytical model previously proposed on the time evolution of the cavity shape is thus shown to be no longer valid for the low-density sphere.     

Backward Terahertz Radiation from a Two-Color Femtosecond Laser Filament

A change in the quasistatic magnetic susceptibility in thin plates of iron borate (FeBO₃), which is a weak ferromagnet, has been revealed at adsorption of water molecules. The measurements have been performed at room temperature with the use of the magneto-optical Faraday effect. The change of the susceptibility in saturated water vapors is about 30%. The observed effect is reversible. The time of establishing the susceptibility after the introduction of water vapors is 1.5 min, which is twice as large as the time of establishing the susceptibility after the evacuation. The effect is explained by the appearance of uniaxial surface magnetic anisotropy in the basal plane because of the adsorption of water molecules.     

Coupling and loading measurements for a dielectric-filled ICRFwaveguide coupler

Experiments were carried out to verify models of the reflection coefficients and the phase transitions for matched or loaded dielectric-filled waveguide couplers in the ion cyclotron range of frequencies (ICRF). A model for the plasma load simulation in the waveguide is developed and examined permanently using the time-domain features of an HP·8510 network analyzer. The loss properties of deionized water, which was used for laboratory waveguide dielectric tests, are also discussed. Close agreement between the coupling models and measurements is noted. For a matched coupler, the optimal power-coupling efficiency obtained is 95% and for a simulated-plasma loaded coupler this value is in the range of 80%, depending upon the plasma load. If it is assumed that the effects of the high neutron flux present in a reactor environment on the dielectric strength of water are negligible (or eliminated), and that the dielectric breakdown strength of water is approximately 3 kV/cm at nearly 80% coupling efficiency, the power handling capability of the water-filled coupler is estimated to be in the range of 3-6 MW     

Analysis of pulsed discharge characteristics of solid-state switch (IGBT) based 16?kHz repetition rate, 100?W average power copper–HBr lasers

We present for the first time a comprehensive analysis (both time resolved and time averaged) of the gas-discharge characteristics of a solid-state switch (IGBT) based on high average power (100?W class), high pulse repetition rate (16?kHz) copper?CHBr laser under various excitation conditions. We evaluate various discharge-plasma parameters such as the electrical inductance, electrical resistance, active laser-head voltage, active electrical power, pre-pulse electron density, and axial gas temperature by numerical processing of the measured laser head voltage?Ccurrent waveforms. For the first time, we evaluate fractional losses at various intermediate stages of the circuit elements as well as effective coupling for the laser excitation process during transfer of energy from the wall plug to the laser-discharge plasma. We conclude that irrespective of the capacitive storage input power (P _in), a constant fraction of ~40% of P _in is coupled into the laser-discharge plasma. With a low to moderate specific input power of 0.4?C0.7?kW/?, the tube produced 70?C110?W average output power at an efficiency of????3.2?C2.8%, respectively. The average laser performances at various P _in are correlated to its time-resolved and average gas-discharge parameters such as the inter-pulse electron density and axial gas temperature.     

Experimental investigation on self-excited resonances of a cylindrical tube in cross-flow

This paper is devoted to the study of acoustic vibrations induced by a flow upon an air-filled cylindrical tube vertically placed in water. A water pump with adapted piping generates a turbulent flow horizontally canalized in a large laboratory tank (6 m × 4 m × 3 m). The tube is located across this flow and an accelerometer measures vibrations. The signal processing performed on the recorded signals brings out resonance modes of the tube excited by the flow. A theoretical study (tube in air) and complementary experiments (tube in air and in water) are conducted to identify these modes.