Preparation and Storage of Silver Nanoparticles in Aqueons Polymers

以水溶性聚合物为保护剂,采用化学还原法制备了银纳米粒子,分别利用透射电子显微镜、紫外可见光谱、同步光散射光谱等手段对其进行了表征,并探索了制备银纳米粒子的最佳实验条件。通过将银纳米粒子-聚合物溶液进行脱水,得到含有银纳米粒子的固态聚合物膜。将固态聚合物膜重新溶解于水,其水溶液的紫外可见光谱与脱水前的溶液进行了比较,发现两者性质并无明显差异。因此,将银纳米粒子分散固定在聚合物膜中是一种崭新而有效的银纳米粒子制备和存储方法。     

Effect of magnetic field on the stimulated photon echo in ytterbium vapors

Polarization of the stimulated photon echo (SPE) at the 0 ? 1 transition in ytterbium vapors in the presence of a longitudinal magnetic field of 0–40 G is experimentally and theoretically studied. The SPE is generated using three light pulses with identical linear polarizations, so that the SPE polarization is the same at zero magnetic field. In the presence of a weak magnetic field, the SPE polarization vector rotates around the magnetic field vector and the depolarization of the SPE signal takes place. Each of the SPE polarization components exhibits biharmonic oscillations depending on the magnetic field. In the presence of a strong magnetic field, these oscillations vanish and the SPE becomes depolarized. The experimental data are in qualitative agreement with the results of the numerical calculations performed with the method of the evolution operator for the finite-duration excitation pulses. The application of the results for the processing of optical data is discussed.     

Application of Optical Techniques to Investigation and Identification of Microorganisms: a Review

Optics and Spectroscopy - Identification and investigation of microorganisms plays a central role in the diagnostics of infectious diseases; therefore, implementation of novel technologies to...     

核形变对J/ψ压低的效应

用强子和弦级联模型,JPCIAE,研究(200A GeV)U+U中心碰撞中核形变对J/ψ压低的效应.结果表明:在两形变核的长轴都沿束流方向的碰撞中,J/ψ压低因子约为两长轴都垂直于束流方向碰撞时的二分之一.     

158A GeV的相对论重离子碰撞的强子快度分布及温度拟合

针对最近NA49在158A GeV的实验(C+C,Si+Si,Pb+Pb)数据,应用LUCIAE3.0模型进行模拟,得到了强子的快度分布和横向动量分布,并与实验数据进行比较,发现基本与实验数据相吻合。并对横向动量分布进行温度拟合,给出了和实验数据吻合很好的结果,但是对于重系统或重强子LUCIAE3.0给出的结果与实验符合相对较差.     

A phenomenological theory for polarization flop in spiral multiferroic TbMnO<Subscript>3</Subscript>

A phenomenological Landau theory has been used to explain magnetic field-driven polarization flop in TbMnO ₃. The Néel wall-like magnetic structure in spiral multiferroics induces a space-dependent internal magnetic field which exerts a torque on spins to rotate bc-spiral to ab-spiral. The external magnetic field is argued to be competing with easy axis anisotropy and the system stabilizes when anisotropy is minimum. With the help of Landau free energy with DM magnetoelectric coupling and a general ansatz for magnetization, the phenomenon of polarization flop has been explained. Relation between T_flop and critical magnetic field has been established and found to be in good agreement with the experiment. This could be an indication that anisotropy of the system is temperature- and magnetic field-dependent.     

Photon echo generated at the transition 0–1 in ytterbium vapor

Photon echo generated at the inter-combination transition (6s ²) ¹ S ₀ ? (6s6p) ³ P ₁ of ¹⁷⁴Yb was investigated for pure ytterbium vapor and for its mixtures with atomic buffers. In pure ytterbium vapor, the polarization of photon echoes at this 0?C1 transition coincides with the polarization of the second exciting pulse for all combinations of linear and circular polarizations of exciting radiation pulses. Photon echo does not appear either for linear orthogonal or for opposite circular polarizations of exciting pulses in pure ytterbium. In mixtures of ytterbium with atomic buffers (Kr, Xe), collision induced photon echo arises only for exciting pulses of linear orthogonal polarizations, its power is essentially less than that of the ordinary echo generated by pulses with parallel polarizations in the same mixture. Polarization of collision induced echo is linear, and it coincides with polarization of the first exciting pulse. Experimental results agree with calculations, and they confirm that the collision induced photon echo at this transition arises exclusively due to anisotropy of depolarizing collisions.     

高能重离子碰撞中正负荷电粒子比单事例起伏研究

用强子和弦级联模型,JPCIAE及相应的Monte Carlo事例产生器,研究相对论性核–核碰撞中有限快度区间内正负荷电粒子比单事例起伏与能量、中心度、共振态衰变及快度间隔的关系.JPCIAE模型能够较好地符合CERN/SPS能区Pb+Pb碰撞的实验结果.本文还用此模型预言了RHIC能区Au+Au碰撞和ALICE能区Pb+Pb碰撞中的正负荷电粒子比单事例起伏.可以看出碰撞能量、中心度、共振态衰变及快度间隔对正负荷电粒子比单事例起伏的影响都不大.