电子俘获材料CaS∶Eu,Sm光谱特性研究

研究了电子俘获材料CaS∶Eu,Sm多晶粉末的紫外-可见-红外吸收光谱及红外激励光谱.研究结果表明,CaS∶Eu,Sm中主激活剂Eu和辅助激活剂Sm分别以Eu2 离子和Sm3 离子的形式存在;ETM的吸收差谱及红外激励光谱所反映的光谱特性是不同的.紫外-可见光区的吸收差谱给出了ETM光谱存储灵敏度的信息,而红外光谱区的吸收差谱给出了ETM所俘获电子数量的信息及电子陷阱能级的特征(深度和宽度)信息.红外激励光谱则反映了ETM将不同波长的红外激励光的能量转换为特定波长处的红外辐射光能量的光谱转换灵敏度.二者结合起来可以更完整地描述ETM的光谱特性.     

The S-FFT calculation of Collins formula and its application in digital holography

We study analytically and numerically the properties of one-dimensional chain of cold ions placed in a periodic potential of optical lattice and global harmonic potential of a trap. In close similarity with the Frenkel-Kontorova model, a transition from sliding to pinned phase takes place with the increase of the optical lattice potential for the density of ions incommensurate with the lattice period. We show that at zero temperature the quantum fluctuations lead to a quantum phase transition and melting of pinned instanton glass phase at large values of dimensional Planck constant. After melting the ion chain can slide in an optical lattice. The obtained results are also relevant for a Wigner crystal placed in a periodic potential.     

Temperature dependence of the electric field gradient in GaN measured with the PAC-probe 181Hf

A radial inhomogeneous magnetic field produced by counter-propagating currents in anti-Helmholtz configuration coils has been superimposed to a Penning trap. The confinement properties of electrons in such a trap have been studied experimentally. Without the radial B-field we find a number of operating conditions where instabilities occur, arising from higher order contributions to the quadrupolar trapping field. When we apply the radial field the trap properties remain essentially unchanged until the strength of this field at the boundary of the electron cloud is of the same order as the homogeneous Penning field. Then a sudden breakdown in the confinement appears. The experiments have been performed in low magnetic fields. The equations of motions of the trapped particles can be cast in a dimensionless form and our results can be considered as independent of the field strength. Contribution was presented at the TCP06, Vancouver Island, 2006.     

Two-period model for calculation of level populations in subbands of multi-period quantum-cascade superlattice structures

For two periods of quantum-cascade laser structures, we propose a system of closed balance equations that make it possible to calculate the occupancy of the energy levels, the quasi-Fermi levels, and also the injection current density taking into account different charge carrier scattering mechanisms. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 801–804, November–December, 2007.     

Preparation and characterization of biodegradable magnetic carriers by single emulsion-solvent evaporation

This paper describes a single emulsion-solvent evaporation protocol to prepare PEGylated biodegradable/biocompatible magnetic carriers by utilizing hydrophobic magnetite and a mixture of poly(D,L lactide-co-glycolide) (PLGA) and poly(lactic acid-block-polyethylene glycol) (PLA-PEG) (26:1 by mass) polymers. We characterized the magnetic microspheres in terms of morphology, composite microstructure, size and size distribution, and magnetic properties. Results show that the preparation produces magnetic microspheres with a good spherical morphology, small size (mean diameter of 1.2–1.5 μm) by means of large size distributions, and magnetizations up to 20–30 emu/g of microspheres.     

Theoretical analysis of a simple yet efficient portable magnetic separator design for separation of magnetic nano/micro-carriers from human blood flow

A technology that could physically remove substances from the blood such as biological, chemical, or radiological toxins could dramatically improve treatment of disease. One method in development proposes to use magnetic-polymer spheres to selectively bind toxins and remove them by magnetic filtration. Although magnetic filtration is a developed technology, the clinical boundary conditions described here require a new filter design. We investigated the removal of toxin-bound magnetic carriers from the blood stream using 2-D FEMLAB simulations. The magnetic separator consisted of a permanent magnet with parallel ferromagnetic prisms on the faces and in contact with a straight tube carrying the magnetic-polymer spheres in suspension. We varied the following parameters: blood flow velocity, the size, and number of ferromagnetic prisms, and the ferromagnetic material in both prisms and magnets. The capture efficiency reached maximum values when the depth of the prisms equaled the diameter of the tubing and the saturation magnetization of the prism material equaled twice that of the magnet. With this design a piece of 2 mm (diameter) tube carrying the fluid resulted in 95% capture of 2.0 μm magnetic-polymer spheres at 10 cm/s flow velocity.     

Near-field study of optical modes in randomly textured ZnO thin films

We report on near-field scanning optical microscopy measurements on randomly textured ZnO thin films. These films are commonly used as transparent conducting oxide in thin-film solar cells. Textured interfaces are used to increase the scattering of light, which leads to a better light trapping in the solar cell. Here, both the topography and the local transmission are measured with a tapered fiber tip with very high spatial resolution. By varying the distance of the tip and the wavelength of the incident light, the optical profile is visualized and reveals a strong confinement of light on a subwavelength scale which corresponds to ridges in the surface structure. The confinement of light results from guided optical modes in the ZnO which are accompanied by a modulated evanescent field in air. No corresponding structure to this modulation is found in the topography. These results give new insight for further improvement of light trapping in solar cells.     

Human Serum Albumin Hybrid Incorporating Synthetic Hemes:A Novel O_2-Carrying Hemoprotein

It has long been known that homologous blood transfusion will result in a lot ofserious problems such as viral infections,for example AIDS,hepatitis,antigenicsensitization and GVHD;therefore aggressive testing of donor blood has beenadopted[1 ,2 ] .Even after this introduction,which is time-consuming and expensive,wecould not eliminate all the risks. In the wake of these kinds of pitfalls,production andclinical use of the blood substitutes have emerged.The essential aim of blood substitutei…     

一种高效便捷的红外探测卡

我们利用稀土直接掺杂工艺 ,通过向带隙宽为 4～ 5ｅＶ的ⅡＡ ⅥＡ族化合物中掺入稀土离子Ｅｕ、Ｓｍ ,合成了电子俘获材料 (ＥＴＭ ＥｌｅｃｔｒｏｎＴｒａｐ ｐｉｎｇＭａｔｅｒｉａｌ)ＣａＳ :Ｅｕ ,Ｓｍ。该材料具有红外上转换和光存储特性 ,其红外响应光谱宽 ( 0 .8～ 1 .6μｍ)、量子转换效率高达 76% [1 ,2 ] 、热稳定性好、使用方便 (室温下工作 ,不需制冷 )、造价低 ,并且具有“常光充能”特性 ,即不需紫外线预激发就能在室温下将红外光 ( 0 .8～ 1 .6μｍ)直接转换为醒目的可见红光 ,是一种优良的红外探测材料 ,利用该材料制作的…     

A Theoretical Study on Nonadiabatic Trapping Models of the Reaction NH H←→N H_2

ThehydrogenatomtransferreactionNH H-N H,isanimportantreactioninradicalreactionsandthegas-phrasethermatdecompositionofammonia.Therewereseveralstudiesonthisreactioninexperiment]andtheory='3.Inthispaper,wehaveemployedtheunifiedstatisticaltheory'(UST)tos...