Electronic and optical properties of the zinc-blende structured LiZnN under pressure

The electronic and optical properties of the cubic zinc-blende (ZB) structured filled tetrahedral semiconductor α-LiZnN under pressure are investigated by using \textit{ab initio} plane wave pseudopotential density functional theory method within the generalized gradient approximation (GGA). The electronic band structure and the density of state under pressure are systematically described. The basic optical constants, including the reflection and absorption spectra, the energy-loss function, the complex refractive index and the dielectric function, are calculated and analysed at different external pressures. Our results suggested that the ZB α-LiZnN is transparent in the partially ultra-violet to the visible light region, and it seems that the transparency is hardly affected by the pressure.     

Influence of substrate temperature on electrical and optical properties of p-type semitransparent conductive nickel oxide thin films deposited by radio frequency sputtering

Nickel oxide thin films were deposited on fused silica and Si(1 0 0) substrates at different substrate temperatures ranging from room temperature to 400 °C using radio frequency reactive magnetron sputtering from a Ni metal target in a mixture of O₂ and Ar. With the increase of substrate temperature, nickel oxide films deposited on the Si substrates exhibit transition from amorphous to poly-crystalline structures with different preferred orientations of NiO(2 0 0) and (1 1 1). The films deposited at higher temperature exhibit higher Ni²⁺/Ni³⁺ ratio. With substrate temperature increasing from room temperature to 400 °C, the electrical resistivities of nickel oxide films increase from (2.8 ± 0.1) × 10⁻² to (8.7 ± 0.1) Ω cm, and the optical band-gap energies increase from 3.65 to 3.88 eV. A p-nickel oxide/n-zinc oxide heterojunction was fabricated to confirm the p-type conduction of nickel oxide thin film, which exhibited a steadily rectifying behavior.     

发光型主体分子胍基芘识别二羧酸根阴离子

在质子性溶剂甲醇中，发光型主体分子胍基芘通过氢键与二羧酸根阴离子结合，自组装形成2：1的主客体超分子复合物，本文采用前表面反射荧光检测，通过跟踪主体分子结合客体前后芘的激基二聚体与单体荧光强度比值的变化，研究了胍基芘对不同酸根数目，不同取代位置的苯取代羧酸盐，磺酸盐，长链二羧酸盐以及双羧基氨基酸的识别能力和识别选择性，结果表明，胍基芘对二羧酸根阴离子的识别能力与客体分子中两个羧基间的距离，分子的平面构型以及取代基的种类密切相关，1，2，4，5－苯四甲酸根的识别效果远远好于其他二羧酸根阴离子。     

用液流操纵单个DNA分子形成纳米悬链线图形

首先用液流拉伸单分子DNA,使其吸附在修饰过的云母基片上.然后让二次液流沿着垂直于已拉伸的DNA的方向流过云母片,用原子力显微镜(AFM)观测,可见DNA单分子片段在基片上形成了一些纳米尺度的悬链线.提出一种“S悬桥”模型能定量地解释这一现象.该研究工作揭示,在DNA的单分子操作中,经典的弹性力学理论足以描述和控制DNA分子二维图形的形成 关键词： DNA 单分子DNA操纵 原子力显微镜(AFM) 纳米悬链线     

经典不确定关系到量子不确定关系的推广及对世界稳定性的应用

一般地引入了经典统计力学的联合概率密度分布,并把其密度函数一般地推广为一般的复函数和它的复共厄的乘积,进而自然地把经典统计力学平均值推广到量子力学的平均值,首次依据联合概率密度分布把经典统计力学的不确定关系严格地推广到量子力学的不确定关系,给出了经典统计力学与量子力学中不确定关系的对应关系,发现了人们对经典统计力学与量子力学不确定关系推导时所各遗漏的一个重要的条件,对不确定关系与此相关的所有的相关文章和书都需修正.最后一般地阐明了世界的稳定性与不确定关系的联系,同时一般地给出了不确定关系失效的条件.     

类金刚石薄膜在硅基底上的沉积及其热导率

采用分子动力学方法模拟了碳在晶体硅基底上的沉积过程, 并分析计算了所沉积的类金刚石薄膜的面向及法向热导率. 对沉积过程的模拟表明, 薄膜密度及sp³杂化类型的碳原子所占比例均随沉积高度的增加而减小, 在碳原子以1 eV能量垂直入射的情况下, 在硅基底上沉积的薄膜密度约为2.8 g/cm³, sp³杂化类型的碳原子所占比例约为22%, 均低于碳在金刚石基底上沉积的情况. 采用Green-Kubo方法, 计算了所沉积类金刚石薄膜的热导率, 其面向热导率可以达到相同尺寸规则金刚石晶体的50%左右, 并且随着薄膜密度与sp³杂化类型碳原子所占比例的升高而升高.     

氮的三原子化合物的从头算及密度泛函研究

在6－311＋G＊基组水平上,对氮的三原子化合物N3^-、N3、N3^+,用MP2及六种密度泛涵方法进行了研究。结果表明,对于已知结构的化合物和计算结果与实验测定值非常吻合,对实验上未知的化合物分子的稳定几何构型及其有关参数进行了新的探讨和补充,同时比较了N3^-、N3、N3^+间相对稳定性和几何性质,并讨论了几种不同方法对该化合物系列诸性质参数的影响,结合MO理论及成键能的计算结果进行了成键分析。     

基于磁场调制的质子放疗新方法及其调制机制

提出一种基于磁场调制的质子放射治疗新方法, 探索肿瘤剂量、正常器官剂量与磁场调制方法之间的关联机制, 研究磁场调制质子放疗在器官环绕型肿瘤(肿瘤被正常器官环绕或包围)治疗中的应用。基于蒙特卡罗粒子输运程序Geant4,分别建立了理想器官环绕结构（由若干平行六面体结构组成）和含胰腺肿瘤人体腹部解剖结构两种几何构型。分别对两种几何构型内部施加磁场, 通过改变磁场强度和方向,调制质子束布拉格峰几何位置, 利用质子径迹的磁致偏转效应使质子束绕开正常器官对肿瘤进行照射。 对于理想器官环绕型构型, 磁场调制质子放疗可在保证95%剂量覆盖肿瘤情况下将受质子照射正常器官体积控制在接近于零的极低水平。对于胰腺肿瘤解剖构型, 磁场调制方法可使质子束在调制磁场作用下, 绕过脊髓和肾脏照射肿瘤, 并使肿瘤被95%剂量较好地覆盖。通过磁场调制, 可对质子束布拉格峰几何位置和质子径迹弯曲程度进行调制, 绕过正常器官对肿瘤进行照射,从而最大限度地减少正常器官的受照体积和剂量。     

Optical switching studies of an azobenzene rigidly linked to a hexa-<Emphasis Type="Italic">peri</Emphasis>-hexabenzocoronene derivative in solution and at a solid–liquid interface

Arrays of test structures consisting of sub-150 nm wide beams were lithographically fabricated in poly(methyl methacrylate) (PMMA) and used to measure the elastic mechanical properties of the material. Capillary forces that arise during the drying of rinse liquids from the test structures caused the nanoscale polymer beams to deform. The initial capillary forces were defined by the test structure geometry, and the magnitudes of the forces were quantified using a two-dimensional Young–Laplace equation. The deformation of the nanostructured beams was measured experimentally and compared to a model based on continuum-level bending beam mechanics, thereby enabling the calculation of the Young’s modulus (E) of the material. For PMMA beams greater than 100 nm in width E was calculated to be 5.1 GPa at room temperature, which corresponds closely to the elastic modulus of bulk PMMA. The Young’s moduli of structures with dimensions less than 100 nm were measured to be less than the bulk value and the origin of the decrease is discussed in terms of dimension dependent properties and polymer degradation during fabrication. The polymer nanostructures also were determined to mechanically deform more readily with increasing characterization temperature. PACS 62.25.+g; 68.35.Gy; 81.16.Nd     

双极晶体管中子注量探测器的标定

双极晶体管经中子辐照后会引起直流增益退化,在10⁹~10¹⁶ cm^-2的注量范围内,其直流增益倒数变化与辐照中子注量呈线性关系。对直流增益退化的双极晶体管进行高温退火,能使受到辐射损伤的双极晶体管性能恢复。鉴于此,将双极晶体管进行逆向工程应用,制作成中子注量探测器,经标定后,可实现对中子注量的监测。对探测器的装配结构进行设计后,依托中国工程物理研究院快中子脉冲堆(CFBR-Ⅱ),在10¹²~10¹³ cm^-2的注量范围对3DK2222A型探测器和在10¹³ cm^-2的注量范围对3DG121C型探测器进行标定。在得到探测器损伤常数K的分散性存在较小和较大的两种情况下,确定了分散性较小时的有效取值和应用方法,以及在分散性较大时,采取标定的损伤常数K只能应用在同只探测器上的方案,并通过高温退火实验证实了该方案的可行性。