镶嵌在SiO2薄膜中纳米GaAs颗粒的Raman散射研究

纳米GaAs颗粒通过射频磁控共溅法成功地被镶嵌在SiO_2薄膜中.通过不同基片温度下沉积的薄膜的Raman光谱观察到了明显的声子限域效应.其结果表明:当沉积时基片温度低于200℃时,X射线衍射和Raman散射均表现出非晶结构特征;当基片温度升高到300℃时,薄膜内的GaAs具有闪锌矿结构,同时其结构振动纵光学声子模对应的Raman散射峰将从非晶散射峰中分离出来,但同大块材料相比,该峰表现出明显的宽化和红移;随着沉积时的基片温度进一步提高,其宽化和红移相应地减小. 关键词：     

钛合金微弧氧化过程中电学参量的特性研究

利用自制的数据采集系统研究了恒定电压下TC4钛合金微弧氧化(MAO)过程中有关电学参量随处理时间的变化规律. 结果表明，通电回路中的阴极和阳极峰值电流随处理时间的变化明显分为4个阶段；膜厚度随处理时间的变化明显分为3个阶段；氧化膜的动态正、反向电阻和动态正、反向电阻率也随处理时间分阶段变化. MAO过程中，各时刻的动态正、反向电阻值不同，一般情况下，动态正向电阻大于反向电阻. 对不同处理时间样品的扫描电子显微镜分析表明，MAO膜呈多孔结构并随处理时间变化.     

A Protocol for the Quantum Private Comparison of Equality with χ-Type State

We present a new quantum protocol for comparing the equal information with the help of a semi-honest third party (TP). Different from previous protocols, we utilize the four-particle χ-type states as the information carriers. Various kinds of outside attacks and participant attacks are discussed in detail. One party cannot learn the other’s private information. The TP cannot learn any information about the private information, even about the comparison result or the length of secret inputs.     

Direct ab initio dynamics calculations of the reaction rate for the hydrogen abstraction reaction of NCO with CH4 and C2H6

The kinetics of the hydrogen abstraction reactions NCO + CH₄ (R1) and NCO + C₂H₆ (R2) have been studied over a wide temperature range. The minimum energy paths (MEPs) were calculated at the MP2/cc-pVDZ level and single-point calculations were refined at the G3MP2 level. The rate constants for the title reactions were calculated using canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) contributions. The fitted three-parameter formulae are k ₁ = 2.52 × 10^?22 T ^3.46 exp(2466/T) and k ₂ = 9.8 × 10^?22 T ^3.2 exp(411.8/T) cm³ molecule^?1 s^?1 for (R1) and (R2), respectively. The calculated rate constants were found to be in good agreement with the available experimental data. Deuterium kinetic isotope effects were also investigated. Both reactions show a significant kinetic isotope effect in the low-temperature range.     

Complexation of hypocrellins and bivalent metals and one-electron reduction of the complexes with electron donor

The complexation of HA (or HB) with bivalent metals was examined by UV-Vis andNMR spectroscopy, and all of the complexes obtained have a metal-ligand ratio of 1:1.Thephotoinduced reduction of the complexes of HA-Zn~(2+) and HA Mg2+ (or HB-Zn~(2+), HB-Mg2+)in the presence of 1-benzyl-1,4-dihydro-nicotinamide as the electron donor was investigated byUV-Vis and ESR spectroscopy. The studies demonstrated that illumination of the complexes ofHA(HB)-Zn~(2+) and HA(HB)-Mg~(2+) led to the accumulation of the chelated semiquinone radicalanions.     

氯络二羰基邻氨基苯甲酸铑(Ⅰ)的合成与晶体结构及其对丙烯氢甲酰化反应的催化性能

本文合成了化学式为Rh(CO)₂Cl(O—NH₂C₆H₄COOH)的一价铑羰基化合物。用热谱、质谱、红外光谱等方法进行了鉴定和性质的研究。从单晶体结构的X射线分析表明,在此化合物品体中铑为平面四方形配位,除了两个羰基一个氯之外,苯环上的—NH₂直接与铑配位,两个分子中的羧酸以氢键相连,成为二聚体。该络合物对丙烯氢甲酰化反应有良好的催化作用:在110℃,40公斤/厘米²压力下,用三苯基膦为助催化剂时,最高转化率可达92％,醛选择性100％,正构丁醛/异构丁醛比值可达8.8。     

Cu(I) complexes of 3,3'-polymethylene bridged derivatives of 2,2'-bi-1,10-phenanthroline

A series of 3,3'-polymethylene-2,2'-bi-1,10-phenanthrolines coordinate with Cu(I) to form dinuclear complexes [(CuL)(2)](2+). As the 3,3'-bridge is lengthened from two to four carbons, the ligand becomes more twisted about the 2,2'-bond, favoring dinuclear coordination. The distance between the two copper atoms varies from 2.92 A for the dimethylene-bridged system to 3.59 A for the tetramethylene bridge. Favorable pi-stacking interactions occur between opposing ligands and promote complex formation. Competition experiments indicate that self-recognition is important and only homoleptic complexes are observed. Under equilibrium conditions, formation of the tetramethylene-bridged complex appears to be the most favored while the dimethylene-bridged system is least favored. The intensity of the long wavelength metal-ligand charge-transfer absorption band decreases as the 3,3'-bridge is shortened. Interaction between the two copper centers is evidenced by a splitting of the oxidation wave, and this splitting increases as the Cu-Cu distance is decreased.     

竹红菌素的13位磺化反应和反应机理

在通空气条件下,回流竹红菌甲素(HA)(或乙素,HB)和Na~2SO~3的含1%NaOH强碱性水溶性生成14-脱羟基-15-脱乙酰基竹红菌甲素-13-位磺酸钠(13-SO~3Na-DDHA)(产率30%)和另一种红色的水溶性聚合物。当这一反应在吡啶-水(1:1/V:V)混合溶剂中进行,并用CuO作氧化剂时,只得到13-SO~3Na-DDHA一种水溶性产物(70%产率)。在后一体系中,由于改变了溶剂和氧化剂,使13-SO~3Na-DDHA的制备更加便利。反应体系的ESR研究表明,这一磺化反应首先是通过竹红菌素和Na~2SO~3之间热活化的电子转移进行的。电子转移的结果产生竹红菌素半醌负离子自由基和三氧化硫负离子自由基(SO~3^-)。硝基甲烷酸式负离子猝灭实验证明,由于竹红菌素的13位能在碱性、高温下活化,磺化的关键步骤是SO~3^-对其活化了的13位的亲电进攻。氧化剂在这一反应中的作用为:将产生的竹红菌素半醌负离子自由基氧化至其母体醌,增加反应物的相对浓度,同时使竹红菌素与SO~3^2^-之间的电子转移循环进行,加速SO~3^-的产生。     

Theoretical study on the reaction mechanism of CH2SH + NO2

The mechanisms of CH₂SH with NO₂ reaction were investigated on the singlet and triplet potential energy surfaces (PES) at the BMC-CCSD//B3LYP/6-311 + G(d,p) level. The result shows that the title reaction is more favourable on the singlet PES thermodynamically, and it is less competitive on the triplet PES. On the singlet PES, the initial addition of CH₂SH with NO₂ leads to HSCH₂NO₂ (IM2) without any transition state, followed by a concerted step involving C–N fission and shift of H atom from S to O giving out CH₂S + trans-HONO, which is the major products of the title reaction. With higher barrier height, the minor products are CH₂S + HNO₂, formed by a similar concerted step from the initial adduct HSCH₂ONO (IM1). The direct abstraction route of H atom in SH group abstracted by O atom might be of some importance. It starts from the addition of the reactants to form a weak interaction molecular complex (MC3), subsequently, surmounts a low barrier height leading to another complex (MC2), which gives out CH₂S + trans-HONO finally. Other direct hydrogen abstraction channels could be negligible with higher barrier heights and less stable products.