Cheng Lihong

Reddish Orange Long-Lasting Phosphorescence in KY3F10:Sm3+ for X-Ray or Cathode Ray Tubes

We report a reddish orange long-lasting phosphor of KY3F10:Sm3+ synthesized by a solid-state reaction for applications in x-ray or cathode-ray tubes. The spectrum contains a group of reddish orange emission lines originating from 4G5/2 → 6HJ transitions of Sm3+. The Judd—Ofelt theory is introduced to analyze the optical transitions of the Sm3+ ions. Moreover, phosphorescence characteristics are discussed. The energy charging and release processes of the phosphor are measured and the phosphorescence decay time with 10% of initial intensity is about 40.7 seconds. The order of kinetics and the activation energy are obtained according to the thermoluminescence curve. The phosphorescence mechanism is proposed based on structural analysis and thermoluminescence glow curve measurement.

On the fluorescence enhancement mechanism of Er3+ in germanate glass containing silver particles

The spectral properties of trivalent erbium ions (Er3+) are systematically studied in a melt-quenched germanate glass (60 GeO2-20PbO-10BaO-10K2O-0.1Ag2O) containing silver (Ag) particles. Thermal treatment of the material leads to the precipitation of Ag particles as observed by transmission electron microscopy and confirmed by absorption spectrum for the obvious surface plasmon resonance peak of Ag particles. The fluorescence from Er3+ in the 10-min-annealed sample with Ag particles is found to be 4.2 times enhanced compared with the unannealed sample excited by 488-nm Ar+ laser. A comparison is made between a spectral study performed on the unannealed Er3+-doped sample and the one annealed for 20 min. The data of absorption cross section and Judd—Ofelt intensity parameters show the agreement between the two samples no matter whether there are Ag particles, indicating that the introduction of Ag particles by post-heat treatment has no effect on the crystal field environment of Er3+ ions. The fluorescence enhancement is attributed to the surface plasmon oscillations of Ag particles in germanate glass.

Entanglement Distillation for Mixed States Using Particle Statistics

We extend the idea of entanglement concentration for pure states(Phys. Rev. Lett. {\bf 88}, 187903) to the case of mixed states. The scheme works only with particle statistics and local operations, without the need of any other interactions. We show that the maximally entangled state can be distilled out when the initial state is pure, otherwise the entanglement of the final state is less than one. The distillation efficiency is a product of the diagonal elements of the initial state, it takes the maximum 50%, the same as the case for pure states.We extend the idea of entanglement concentration protocol for pure states (Phys. Rev. Lett. 88, 187903) to the case of entanglement distillation for mixed states. The scheme works only with particle statistics and local operations, without the need of any other interactions. We show that the maximally entangled state can be distilled out when the initial state is pure, otherwise the entanglement distilled depends on the off-diagonal element of density matrix of the initial state. Because of the requirement for density matrix, the entanglement distilled is always less than one, and this result is the same for both fermionic and bosonic particles. The distillation efficiency is a product of the diagonal elements of the initial state, it takes the maximum 50%, the same as that in the case for pure states.

Ba 3 Gd(PO 4 ) 3 :Eu 3+ 荧光粉的合成及发光性质

采用高温固相反应法合成了不同Eu 3+ 掺杂浓度的Ba 3 Gd(PO 4 ) 3 荧光粉。利用X射线衍射对产生的晶体结构进行了分析, 证实产物为纯相, Eu 3+ 的引入没有导致晶体结构的改变。利用Van Uitert模型对 5 D 0 能级荧光的浓度猝灭行为进行了研究, 发现浓度猝灭是由于Eu 3+ 间交换相互作用所导致。分析了 5 D 0 荧光发射的温度依赖, 给出了荧光温度猝灭行为符合横向穿越模型, 并通过非线性拟合获得了激活能。利用Eu 3+ 的发射光谱和荧光衰减数据, 计算了 5 D 0 - 7 F J 辐射跃迁速率及荧光分支比, 同时得到了光学跃迁强度参数。

Dynamics of laser beams in inhomogeneous electron–positron–ion plasmas

Nonlinear interaction of laser and electron–positron–ion plasmas is investigated by invoking the variational principle and numerical simulation, in terms of a nonlinear Schrodinger equation with inhomogeneities effect. It is shown that the plasma inhomogeneity has great influence on the laser beam dynamics. The laser beam can be self-trapped, focused, or defocused depending on the inhomogeneity character. The linearly decreasing axial plasma density makes the laser beam defocus, while the linearly increasing axial plasma density results in self-trapping of the beam. The self-focusing of the trapped beam is found in a high-density region. For the Gaussian types of density distribution, the beam field submits nonlinearly oscillating regime. The results provide an efficient way to manipulate the dynamics of laser beam propagating in plasma.