离子注入对ZnTe:O中间带光伏材料的微观结构及光学特性的影响

II-VI和III-V族高失配合金半导体是新型高效中间带太阳电池的优选材料体系,但中间带的形成及其能带调控等关键问题仍未得到有效解决.采用氧离子注入方式,在非平衡条件下对碲化锌(Zn Te)单晶材料实现了等电子掺杂,深入研究了离子注入对Zn Te:O材料的微观结构和光学特性的影响.研究表明:注入合适浓度的氧离子(2.5×1018cm-3)将会形成晶格应变,并诱导1.80 e V(导带下0.45 e V)中间带的产生;而较高浓度(2.5×1020cm-3)的氧离子会导致Zn Te注入层表面非晶化,并增强与锌空位相关的深能级(～1.6 e V)发光.时间分辨光致发光结果显示,离子注入诱导形成的中间带主要是和氧等电子陷阱束缚的局域激子发光有关,载流子衰减寿命较长(129 ps).因此,需要降低晶格紊乱度和合金无序,实现电子局域态向扩展态的转变,从而有效调控中间带能带结构.     

Al纳米线不同晶向力学行为和变形机制的模拟

采用分子动力学模拟计算方法,考察具有较高层错能的Al纳米线沿不同晶向的力学行为和变形机制。在相同计算条件下与具有较低层错能的Ni、Cu、Au和Ag等FCC金属纳米线进行比较。结果表明：在力学行为方面,Al纳米线的弹性模量呈现明显的结构各向异性,满足E_[111] > E_[110] > E_[100]的关系,这一关系在FCC金属纳米线中普遍成立;Al纳米线的屈服应力随晶向呈现σ_y[100] > σ_y[111] > σ_y[110]的关系,这一关系在具有较低层错能的FCC金属纳米线中不具有普遍性,这与体系中位错形成机制密切相关。根据拉伸变形过程微观结构的演变规律,阐明Al纳米线不同晶向的变形机制,并与具有较低层错能的Ni、Cu、Au和Ag等FCC金属纳米线的变形机制进行比较。结果表明,对于尺度较小的高层错能Al纳米线,Schmid因子和广义层错能均难以准确预测其变形机制。     

探究地磁场对彩色显像管成像的影响

关于显像管电视机的成像原理,高中物理教材仅关注运动的带电粒子在偏转线圈提供的磁场中的偏转.但在实际生活中,地磁场也会对电视机显像管中运动带电粒子的轨迹产生影响.本文立足于高中生的认知能力,从生活实例出发,分析地磁场对彩色显像管成像的影响,细化建模过程,给出真实参数,凸显科学研究方法在教学中的应用,使教学内容与现代科技和生活实际相联系,从而将培养学生的核心素养落实在日常教学之中.     

In situ investigation of synchrotron radiation damage effect of ancient paintings by time-resolved ED-XAS and IR combined techniques

Advanced synchrotron radiation light is a powerful tool for archaeometry research. However, its applications to precious cultural relics, especially for color painting, have been hindered to some degree due to potential X-ray radiation damage. Compared to inorganic mineral pigments, organic binders in the painting are easier to be damaged by synchrotron radiation X-ray beam. The radiation damage effect of two typical painting samples, pure rabbit skin glue and the mixed sample of rabbit skin glue and zinc white, has been investigated by in situ time-resolved ED-XAS and IR combined techniques. The results show that the radiation damage effect of pure rabbit skin glue is more serious at low X-ray energy (7775 eV). The radiation damage effect of the mixed sample increases significantly due to more X-ray absorption by inorganic pigments. Furthermore, the radiation damage is more serious at the energy near Zn K-edge and is somewhat slight at higher energy (13,054 eV). These damages are more obvious from the point of view of protein secondary structures. The irradiation damage effects increase more rapidly at the beginning and are not linear with the irradiating time. The results indicate that synchrotron radiation damage can be reduced effectively by using X-ray energy far away from the X-ray absorption edge of the major element in the pigments during XRF, XRD and CT experiments, or by using time-resolved techniques such as QXAFS and ED-XAS during XAFS experiments.     

可多重聚焦电磁能量的左手材料结构

 功分器在微波工程中广泛应用。基于有损耗的Lorentz模型的时域有限差分(FDTD)方法,分析模拟了左手材料(LHM)的平板结构和环状结构对电磁波源的不同聚焦特性。每个左手材料边界均可以对波源发出的波进行聚焦。同时通过比较,在对称结构中,每个聚焦点的电磁场幅度都相同。说明该左手材料结构可以对电磁波源进行多点聚焦。     

用冲击压缩数据计算物质结合能的一个简便解析方法

 在材料性质满足：（1）可用波恩-迈耶势描述其结合能；（2）自由电子对热能的贡献可忽略不计；以及（3）冲击波速度关系式可用直线关系描述的条件下，本文导出了一个用冲击绝热线数据直接计算该材料结合能和格临爱森物态方程的简便解析公式。给出了用本文方法计算Be，Al，Cu，Ta，U等十七种金属的冷能和冷压方程的结果。将本文结果与徐锡申等和Zharkov等的数值计算结果相比较，发现在冲击压缩测量的实验误差范围内，大多数金属的符合程度是比较好的，但Be，Ni和Pb三种金属除外。本文中对上述偏差的可能原因也做了讨论。     

用级联阵列机构造大型数字式声呐的设计技术

在分析声呐信号处理特点的基础上,提出一种称为级联阵列机的多处理器体系结构,用以实现大型数字式声呐系统。并对该体系结构中的各种要素,包括总线协议,数据传输,基本处理单元进行了详细讨论,最后给出一个使用级联阵列机结构实现数字声响系统的设计步骤。     

Conceptual design of an intense positron source based on an LIA

Accelerator based positron sources are widely used due to their high intensity. Most of these accelerators are RF accelerators. An LIA (linear induction accelerator) is a kind of high current pulsed accelerator used for radiography. A conceptual design of an intense pulsed positron source based on an LIA is presented in the paper. One advantage of an LIA is its pulsed power being higher than conventional accelerators, which means a higher amount of primary electrons for positron generations per pulse. Another advantage of an LIA is that it is very suitable to decelerate the positron bunch generated by bremsstrahlung pair process due to its ability to adjustably shape the voltage pulse. By implementing LIA cavities to decelerate the positron bunch before it is moderated, the positron yield could be greatly increased. These features may make the LIA based positron source become a high intensity pulsed positron source.     

荧光色散谱对FeS(X5△)振动常数的实验确认

基于之前的激光诱导荧光激发谱工作,采用激光诱导荧光色散谱技术直接侦测中性FeS基电子态X5￠振动能级到v″=3而获得其振动常数. 所得FeS(X⁵△)振动频率值(518±5 cm^-1)和最近的光电子能谱测量值(520±30 cm^-1) [J. Phys. Chem. A 107, 2821 (2003)]符合得较好,该光电子能谱测量值是之前唯一报道的FeS电子态振动频率的实验值. 通过比较实验结果和相关文献(主要来自理论预测),确定FeS的基态是X⁵△态.