General formula for phonon-assisted n-photon absorption in solids

A general formula for phonon-assisted n-photon absorption in solids is obtained by (n+1)-th order perturbation technique. The complicated calculation process for transition element of n-photon absorption is simply demonstrated by a diagram approach that is proposed in this work. We find that the transition element for the n-photon absorption has a simple form, i.e., it is just the first term of the n-th order fist kind Bessel function.     

Structural, electronic and magnetic properties of the Mnben Ni(110) c(2×2) surface alloy

Using first-principles total energy method, we study the structural, the electronic and the magnetic properties of the MnNi(110) c(2×2) surface alloy. Paramagnetic, ferromagnetic, and antiferromagnetic surfaces in the top layer and the second layer are considered. It turns out that the substitutional alloy in the outermost layer with ferromagnetic surface is the most stable in all cases. The buckling of the Mn–Ni(110) c(2×2) surface alloy in the top layer is as large as 0.26á(1á=0.1 n13) and the weak rippling is 0.038 AA in the third layer, in excellent agreement with experimental results. It is proved that the magnetism of Mn can stabilize this surface alloy. Electronic structures show a large magnetic splitting for the Mn atom, which is slightly higher than that of Mn–Ni(100) c(2×2) surface alloy (3.41 eV) due to the higher magnetic moment. A large magnetic moment for the Mn atom is predicted to be 3.81 μ_B. We suggest the ferromagnetic order of the Mn moments and the ferromagnetic coupling to the Ni substrate, which confirms the experimental results. The magnetism of Mn is identified as the driving force of the large buckling and the work-function change. The comparison with the other magnetic surface alloys is also presented and some trends are predicted.     

The influence of nickel dopant on the microstructure and optical properties of SnO2 nano-powders

The microstructure and optical properties of Ni-doped SnO2 nano-powders are studied in detail. By Ni-doping, not only the grain size reduces, but also the grain shape changes from nano-rods to spherical particles. The crystallization becomes better with annealing temperature increasing. The band gap energy decreases as nickel doping level increases. The sp-d hybridization and alloying effect due to amorphous SnO2-x phase should be responsible for the band gap narrowing effect. Nickel dopant does not change the photoluminescence （PL） peak positions.     

天然水晶与水热法合成水晶的近红外光谱对比分析

水热法合成水晶与天然水晶的物理化学性质相似、内含物少见,常规检测方法无法鉴别。本论文采用德国布鲁克(Bruker)TENSOR27红外光谱仪测试分析,发现合成无色水晶以3585cm~(-1)谱带为特征;烟水晶特征吸收峰在3300~3000cm~(-1)附近,而合成烟水晶位于3600~3300cm~(-1)附近;合成黄水晶仅有5200cm~(-1)吸收峰,黄水晶不具有此特征吸收;紫水晶具有5228cm~(-1)、4450cm~(-1)特征谱带,合成紫水晶在4000~3000cm~(-1)内有特征吸收峰;合成绿水晶仅有5200cm~(-1)吸收峰。     

一些天然、合成及仿造宝石的显微拉曼光谱鉴别

本文主要测定部分天然宝石、合成宝石以及仿造宝石 ,以期建立云南宝玉石拉曼光谱数据库 ,进而为鉴别宝石的合成品、仿造品提供标准谱图     

一个不寻常的人λ-型Bence Jones蛋白(Lee)可变区的氨基酸序列

用限制性胰蛋白酶水解,制备了人λ-型Bence Jones蛋白(Lee)的可变区,用还原并氨乙基化的蛋白质制备了溴化氰裂解片段和胰蛋白酶水解肽,测定各肽段的氨基酸序列并根据Lee蛋白和其它λ-链的同源性定出了Lee轻链可变区的氨基酸全序列。Lee轻链的N末端有二个额外氨基酸残基的延伸。Lee蛋白的个体型(idiotypic)抗体能和另外两个λ-型Bence Jones蛋白MCg λ_Ⅳ和Cap λ_Ⅲ反应。用Chou和Fasman的方法预测Lee轻链可变区二级结构的结果表明:Lee轻链可变区表面上有两个部分和Mcg,Cap的相应部分的结构相同,这是这三个蛋白质在免疫学性质上具有个体型相似性的可能解释。     

铀酰萃取剂双亚砜的合成及其微胶囊萃取铀性能的研究

铀是一种非常重要的能源物质 ,现在国际上一般使用磷酸三丁酯 (ＴＢＰ)作为铀的萃取剂提取及回收铀。ＴＢＰ对铀有较强的萃取能力 ,但它耐辐照能力较差 ,有关双亚砜的报道仅局限于ｎ =1 ,2 [1,2 ] 。本文以硝酸为氧化剂 ,采用硫醚氧化法 ,合成了四个新的双亚砜类化合物ＰｈＳＯ(ＣＨ2 ) ｎＳＯＰｈ(ｎ分别为 2、3、4、6) ,并经元素分析、核磁共振对其结构进行了表征。为避免萃取过程中乳化或三相的出现 ,采用界面缩聚法[3 ] 以高分子材料包覆ＴＢＰ和自制的双亚砜类化合物 (ｎ =2 ,4,6) ,制成微胶囊 ,对其在酸性水溶液 (ｐＨ =1～1 .5 )中萃…     

Microstructure evolution of zircaloy-4 during Ne ion irradiation and annealing: An in situ TEM investigation

The microstructural evolution of zircaloy-4 was studied, including the amorphization and recrystallization of Zr（Fe, Cr）2 precipitates, and the density of dislocations under in situ Ne ion irradiation and post annealing. The results show that irradiation at a relatively high temperature and dose induces the formation of nanocrystals in pre-amorphized Zr（Fe, Cr）2 precipitates. The recrystallized nanocrystals also have the structure of hcp-Zr（Fe, Cr）2. The formation of the nanocrystals is thought to be the consequence of competition between atomistic disordering and the recrystallization of precipitates under ion irradiation. The free energy of the nanocrystal is lower than that of the amorphous state, which is another reason for the recrystallization of the precipitates. With increased annealing temperature, the density of the nanocrystals is increased. The dislocation density sharply decreases with the increase in the annealing temperature, and its size increases.     

铒、钪膜中离子注入氦的热解析行为

采用热解析法初步研究了铒、钪膜中离子注入氦的热解析行为。研究结果表明:同种元素铒中离子注入氦的热释放峰位相同,但膜的致密性将影响氦的释放量,结构疏松的膜中存在的孔洞是氦的快速释放通道;在相同注入剂量和能量条件下,铒、钪膜中注入氦的热释放峰位不同,这可能与氦在铒、钪膜中的深度分布及膜的致密性有关,利用质子增强背散射法测量出能量为60 keV的4He+在铒、钪膜中的注入深度分别为210,308 nm。