低速~(40)Ar~(17+)离子入射金属Be表面发射的近红外光谱线和X射线谱

用速度不同的(动能EK=272和357keV,速度v=1.14×106和1.72×106m/s)的高电荷态离子40Ar17+分别入射金属Be表面,同时测量这种相互作用过程中产生的近红外光谱线和X射线谱。实验结果表明,在低速范围内(速度小于玻尔速度vBohr=2.19×106m/s),速度较小的40Ar17+离子在到达金属的表面临界距离Rc到进入表面(2—3原子层)的进程中,形成了较多的高激发态Ar原子,其退激辐射较强的光谱线,进而验证了经典过垒模型。     

基于GEANT4的CsI(T1)闪烁体探测器的Monte Carlo模拟

对闪烁光在晶体内的传输以及光电子倍增过程进行了建模,基于GEANT4软件包对CsI(T1)闪烁体探测器进行了蒙特卡罗模拟,得到了不同形状、尺寸和包装的CsI(T1)晶体测量γ射线的能谱.对比模拟和测试结果,两者得到了很好的符合,从而验证了模拟参数的合理性和可靠性.该模拟程序的建立为闪烁体探测器的设计提供了更精确的开发工具.     

环境友好半导体Mg2Si薄膜的研究进展

介绍了近年来Mg2Si薄膜的研究进展。从Mg2Si材料的晶体结构出发,重点对Mg2Si薄膜的基本性质、制备方法和应用前景进行了论述。研究表明,Mg2Si是一种窄带隙间接半导体材料,在光电和热电领域都具有较好的应用价值,因其兼具了组成元素地层含量丰富、无毒、无污染等优点,被视为是一种新型的环境友好半导体材料。在Mg2Si薄膜的外延生长技术方面,目前比较成熟的方法有分子束外延、脉冲激光沉积、反应扩散等多种,但普遍存在制备条件较苛刻,成膜质量不高等缺点。最后,对目前存在的问题及未来的研究动向做了简要讨论。     

Study of scalar meson a0(980) from B→a0(980)π decays

In this paper, we calculate the branching ratios and the direct CP-violating asymmetries for decays B0 →a00(980)π0, a0+(980)π-, a0-(980)π and B- →a00(980)π-, a0-(980)π0 by employing the perturbative QCD (pQCD) factorization approach at the leading order. We found that (a) the pQCD predictions for the branching ratios are around (0.4 - 2.8) × 10-6, consistent with currently available experimental upper limits; (b) the CP asymmetries of B0→ao(980)π0 and B-→a0-(980)π0 decays can be large, about (70-80)% for α = 100°.     

基于FPGA的半导体激光器温度控制系统设计

介绍了半导体激光器的温度控制原理,设计了基于FPGA的半导体激光器温度控制系统。系统采用数字温度传感器DS18820作为温度测量器件,TEC作为控温执行元件,并采用模糊控制算法、PWM机制来控制TEC的驱动电流从而实现温控。基于QuartusⅡ开发平台采用Verilog HDL设计了软件部分,最后进行了功能仿真。整个系统对硬件要求不高,实现简单。从仿真结果可以看出,控制系统能够满足半导体激光器温度控制的精度和稳定度的要求。     

生物模板法合成三元硫化物及其抑菌活性

分别以橡胶乳、大豆粉、三七粉、菠菜提取物、苝醌提取物作为模板剂,采用溶剂热合成法,合成了具有不同形貌的三元硫化物,考察了其对枯草芽孢杆菌的抑菌活性性能,同时通过MTT法对三元硫化物材料进行毒性测试。通过XRD和SEM进行表征。结果表明：具有棒状结构的Bi₂S₃、雪花状的AgBiS₂、以及含有毛刺状小球的Cu₃BiS₃材料具有特殊的抑菌,且对正常细胞的毒性较低甚至没有。      

一种共轭结构三苯胺衍生物的制备及光学性质

通过固相Wittig反应合成了一种π共轭结构有机荧光化合物。其结构经¹HNMR、¹³CNMR、IR及ESI-MS表征。通过实验研究了化合物的UV-Vis和荧光光谱并采用理论计算进行了光谱机理解释。目标化合物在二氯甲烷、乙酸乙酯、乙醇、乙腈和N, N-二甲基甲酰胺中的最大吸收波长λ_max均位于310 和380 nm处,在上述溶剂中的最强荧光发射波长λ_em分别为438、436、439、448和451 nm。      

Thermodynamic Performance Characteristics of a Brownian Microscopic Heat Engine Driven by Discrete and Periodic Temperature Field

A Brownian microscopic heat engine with a particle hopping on a one-dimensional lattice driven by a discrete and periodic temperature field in a periodic sawtooth potential is investigated. In order to clarify the underlying physical pictures of the heat engine, the heat flow via the potential energy and the kinetic energy of the particles are considered simultaneously. Based on describing the jumps among the three states, the expressions of the efficiency and power output of the heat engine are derived analytically. The general performance characteristic curves are plotted by numerical calculation. It is found that the power output-efficiency curve is a loop-shaped one, which is similar to one for a real irreversible heat engine. The influence of the ratio of the temperature of the hot and cold reservoirs and the sawtooth potential on the maximum efficiency and power output is analyzed for some given parameters. When the heat flows via the kinetic energy is neglected, the power output-efficiency curve is an open-shaped one, which is similar to one for an endroeversible heat engine.     

B→K0^＊（1430）η（＇） decays in the pQCD approach

Based on the assumption of two-quark structure of the scalar meson K0^＊（1430）, we calculate the CP-averaged branching ratios for B→K0^＊（1430）η（＇） decays in the framework of the perturbative QCD （pQCD） approach here. We perform the evaluations in two scenarios for the scalar meson spectrum. We find that： （a） the pQCD predictions for Br（B→K0^＊（1430）η（＇）） which are about 10^-5 10^-6, basically agree with the data within large theoretical uncertainty; （b） the agreement between the pQCD predictions and the data in Scenario Ⅰ is better than that in Scenario Ⅱ, which can be tested by the forthcoming LHC experiments; （c） the annihilation contributions play an important role for these considered decays.     

B→（J/ψ,η_c）K decays in the perturbative QCD approach

In this paper,we calculated the B →（J/ψ,ηc） K decays in the perturbative QCD（pQCD） factorization approach with the inclusion of the partial next-to-leading order（NLO） contributions. With the inclusion of the significant enhancement from the NLO vertex corrections,the NLO pQCD predictions for the branching ratios agree with the data within 2σ errors：Br（B0 → J/ψK0） = 5.2-＋32..58×10-4,Br（B＋ → J/ψK＋） = 5.6-＋32..79×10-4,Br（B0 →ηcK0） = 5.5-＋22..30 × 10-4,Br（B＋ →ηcK＋） = 5.9-＋22..51 × 10-4.