氮化硼薄膜内应力的红外光谱研究

用射频(RF)磁控溅射制备了立方氮化硼(c-BN)薄膜。FTIR光谱和电子衍射实验表明:该薄膜是纯的,其结晶度很高。FTIR光谱研究指出,基板负偏压是c-BN相形成的重要因素,但也由此产生了c-BN薄膜的应力,且负偏压越高,产生的应力越大。比较透射谱和反射谱的结果,c-BN薄膜表面层的应力小于内部的。按照c-BN形成的压力模型,表面应力小到一定程度可能影响c-BN的继续生长。一个特制的分层结构BN薄膜保留了由于应力造成的c-BN的裂纹,这个裂纹分布在一些同心圆上,中心是缺陷或杂质,同心圆之间有明显的分界线,把c-BN表层分割成许多应力区。     

The Effects of Methylene Blue on the Optical Properties of Nanometer-sized CdS Organosol

The inverse micelle system of nanometer-sized CdS doped with Methylene Blue(MB) was synthesized and characterized by using absorption and fluorescence spectra. The results show that MB molecules were absorbed onto the surface of CdS nanoparticles and interacted with surfactants when its concentration was lower than 4×10^-6 mol/L. From the comparison of their spectra, MB molecules by adsorption have a strong quenched fluorescence emission of CdS nanoparticles with surface defect states. All responses and main mechanism are ascribed to the charge transfer between the CdS organosol and Methylene Blue molecules.     

Generation of Entanglement Between Two Noninteracting Qubits via Interaction with Nonclassical Radiation Field

We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state.     

高压下稀土离子的电子态

给出了稀土离子电子态在高静水压下的某些特性,包括高压下的发光光 谱及能级特性,晶体场强度的压力效应,4f电子库仑排斥及自旋轨道耦合等作用随压力 的变化等。     

纳米材料与物理学

简述了纳米材料的发展过程,讨论了纳米材料的电子结构,提出了纳米材料研究中的物理问题。     

U91+离子碰撞强度和速率系数的相对论理论计算

介绍了用相对论多通道理论结合量子亏损理论计算电子碰撞激发过程的方法。用此方法计算了Ｕ＾９１＋离子电子碰撞激发的碰撞强度和有效碰撞强度及速度系数。与Ｒ矩阵方法的计算结果比较表明：在激发能量阈附近还有一组共振结构;目前的方法对共振结构的描述更精细完整。根据碰撞强度,通过对电子速度的麦克斯韦分布积分得到了有效碰撞强度与温度的关系。可以看出,碰撞强度在能量阈值附近的共振峰值使低温１ｓ－２ｓ跃迁有效碰撞强度     

Chirped Bragg光纤光栅的优化设计与优化指数

根据线性ChirpedBragg光纤光栅的一般原理 ,探讨了不同啁啾系数 ,准高斯耦合函数对Bragg反射光栅的反射率及色散补偿特性的响应。结果表明 :增大啁啾系数以及选取适当的准高斯耦合函数 ,在保证反射率较大的情况下 ,能有效地改善色散补偿特性。通过引入微波领域的“优化指数”这一概念 ,量化了色散补偿器的补偿能力。     

激光多普勒测量中信号的误差分析

激光多普勒测量技术在流体以及固体表面测量中得到了广泛的运用。由于影响测量的误差源较多 ,因而在实际的测量过程中 ,激光多普勒测量的精度并不是非常的高。影响测量精度的误差主要是激光多普勒频率增宽 ,高斯光束的干涉以及安装误差。通过控制不同的系统参数 ,可以消除或减小相应的误差     

完全三部图K(n_1,n_2,n_3)的色唯一性

设G是简单图,用P(G,λ)表示图G的色多项式.若对任意简单图H使P(H,λ)=P(G,λ),都有H与G同构,则称G是色唯一图.令K(n     

Nano-Patterning via Molecular Self-Assembly

Surface patterning with microscopically defined structures is a rapidly developing topic, although it is still a challenge for generating patterned surface in the size range of nanometer. Molecular assemblies normally in the size range of 1 to 102 nm should overcome easily the conventional lithographic limit. Although many techniques have been developed to generate patterned surface, surface patterning totally directed by molecular self-assembly has been less addressed. For this purpose, ways of molecular self-assembly to generate regular arrays of nanostructures have been demonstrated in our laboratory including chemisorption of dendron-thiols,surface adsorption of bolaform amphiphiles, and nano-phase separation of rod-coil diblock molecules. As to be discussed, molecular self-assembly is an alternative but effective way to produce patterned structures, particularly in the range of a few nanometers.