原子镁的电子碰撞电离

使用Ｒ－矩阵方法，在扭曲库仑－玻恩非交换近似下（ＤＣＢＮＸ）采用二态密耦图象，计算了原子镁从电离阈值附近到１００ｅＶ范围的电子碰撞电离截面。从能量微分截面可看到明显的Ｒｙｄｂｅｒｇ系列共振。     

注入离子漂移管技术测量原子团簇结构

团簇结构测量是团簇科学研究中的一个重要课题。文章对近几年发展的注入离子漂移管技术进行了详细介绍与分析，该技术是上前测量团簇结构近似程度最高的技术，已在Ｃ，Ｓｉ，Ｇｅ及Ａｌ等原子团簇的结构研究中获得广泛应用，并取得了许多重要结果。     

基于二维声子晶体第一带边态的声学定向辐射

采用多重散射方法研究二维四方钢/水声子晶体中线源的辐射问题。数值结果表明利用声子晶体ΓΜ方向的第一带边态可以实现声定向辐射。利用文中设计的三角形晶体结构既可以实现声波的单束定向辐射,还能够得到传播方向互相垂直的双束定向辐射。该研究对声子晶体功能器件的设计具有一定的意义。     

Lessons from nature: biomimetic subwavelength structures for high‐performance optics

In nature, optical structures in the subwavelength range have been evolved over millions of years. For example, in the form of ‘moth‐eye’ structures they show a strong anti‐reflective effect on the compound eyes of night‐active insects and therefore offer a successful protection over predators. In this contribution the advantages and challenges to transfer this natural concept of subwavelength structured optical interfaces to high‐end optical systems are discussed. Here, in comparison to alternative conventional multilayer systems, the bioinspired anti‐reflective structures offer a wide wavelength range and a broad angle dependency. Additionally, adhesion problems are reduced drastically. Simultaneously to the theoretical consideration of the best profile form of the subwavelength structures, appropriate realization technologies have been developed in recent years, where both top‐down and bottom‐up approaches have been investigated. Depending on the choice of the structuring technique, anti‐reflective subwavelength structures are applicable to a wide spectrum of optical elements ranging from micro‐optical components to aspheres for applications in imaging and also illumination setups of high‐end optical instruments.     

覆盖度对S原子在Ir(001)表面吸附性质的影响

采用第一性原理方法模拟了覆盖度对S原子在Ir(001)表面吸附能和电子结构的影响。结果表明：在覆盖度0.50 ML以下,S原子吸附在Hollow空位最稳定,且吸附能几乎不随覆盖度变化;在覆盖度0.66 ML以上吸附能随覆盖度增加而减小。吸附体系金属表面d带电子结构随覆盖度变化与O/Pt(111)吸附体系相似。这些结果与Hammer-Nørskov模型吻合。     

CoBn(n≤19)团簇结构、电子性质和磁性的密度泛函理论研究

采用密度泛函理论中的广义梯度近似(Generalized Gradient Approximation, GGA)方法, 对不同自旋多重度的CoBn(n≤19)团簇的平衡几何结构、电子性质和磁性进行了研究. 随着尺寸的增加, CoBn(n≤19)团簇最低能量结构从平面结构逐步演变为立体结构, Co从主团簇的外部向内部转移. 团簇最低能量结构的二阶能量差分表明CoB3、CoB7、CoB10、CoB12、CoB14和CoB16团簇较相邻团簇稳定. Co的掺杂增强了硼团簇的化学活性. 最低能量结构中Co的d轨道和B的p轨道存在着明显的杂化. 当n<13, Co处于主团簇的外部时, Co的带电量为正, Co具有磁矩. 当n≥13, Co处于主团簇的内部时, Co的带电量为负, Co的磁矩几乎为零. 团簇最低能量结构的总磁矩主要来自Co的3d轨道的贡献, 且总磁矩随团簇尺寸增大呈现奇偶振荡.     

Theoretical validation on the existence of two transverse surface waves in piezoelectric/elastic layered structures

In this paper, we analytically study the dispersion behavior of transverse surface waves in a piezoelectric coupled solid consisting of a transversely isotropic piezoelectric ceramic layer and an isotropic metal or dielectric substrate. This study is a revisit to the stiffened Love wave propagation done previously. Closed-form dispersion equations are obtained in a very simple mathematical form for both electrically open and shorted cases. From the viewpoint of physical situation, two transverse surface waves (i.e., the stiffened Love wave and the FDLW-type wave) are separately found in a PZT-4/steel system and a PZT-4/zinc system. All the observed dispersion curves are theoretically validated through the discussion on the limit values of phase velocity using the obtained dispersion equations. Those validation and discussion give rise to a deeper understanding on the existence of transverse surface waves in such piezoelectric coupled structures. The results can be used as a benchmark for the study of the wave propagation in the piezoelectric coupled structures and are significant in the design of wave propagation in the piezoelectric coupled structures as well.     

Orbital-decomposed electronic and magnetic properties of the double perovskite Sr2FeReO6

The detailed orbital-decomposed electronic structures and magnetic properties of the double perovskite Sr₂FeReO₆ have been studied using the first-principles projector augmented wave (PAW) potential within the generalized gradient approximation (GGA). Both occupied and unoccupied s and three p states of Fe³⁺ ion are located far away from the Fermi level, while all up-spin states and most down-spin states are completely filled for the s and three p states of Re⁵⁺ ion. The octahedral crystal field of the oxygen atoms around transition-metal (TM) sites splits the five-fold degenerate d states of the free TM atoms into triply degenerate t_2g states with smaller bonding-antibonding splitting and doubly degenerate e_g states with larger bonding-antibonding splitting. The Fe³⁺ and Re⁵⁺ ions are in the states (3d⁵, S=5/2) and (5d², S=1) with magnetic moments 3.70 and −0.86μ_B, respectively and thus antiferromagnetic coupling via oxygen between them. There are no direct interactions between two nearest Fe-Fe or Re-Re pairs, whereas along each Fe-O-Re-O-Fe or Re-O-Fe-O-Re chains, the hybridizations between Fe 3d and 4s, O 2s and 2p, as well as Re 5p, 5d and 6s orbitals are fairly significant.     

EXAFS results on metallic amorphous alloys and on metallurgy

Summary A review of some general trends of EXAFS in alloys and metallic glasses is given. The intrinsic qualities of the EXAFS method in metallurgy, structure of amorphous materials, clustering and spin glasses are discussed. Paper presented at the Workshop on ?EXAFS Data Analysis in Disordered Systems?, held in Parma, October 5–7, 1981.     

钢筋腐蚀监测的光波导传感方法原理探索

本文提出了一种用于混凝土结构钢筋腐蚀监测的光波导传感方法,该方法利用金属膜层局部取代光波导的介质包层,构成腐蚀敏感膜,从而获取金属腐蚀信息.本文依据波导理论讨论了该方法的原理,利用电化学方法在721比色皿的石英玻璃上证实了平面光波导腐蚀传感方案的可行性,并进一步用电镀方法制备出了光纤腐蚀传感器(FOCS)实验样品,取得了预期实验结果.