北京自由电子激光最近进展──实现饱和振荡

北京自由电子激光(BFEL)装置于1993年底在10.68μm处实现了饱和振荡.输出激光能量为3mJ,饱和平顶宽度2μs.对应饱和振荡平均功率为210kW(宏脉冲),峰值功率约为20MW,比自发辐射高8个量级,单程小讯号净增益为24%,转换效率为0.45%,与理论预期结果相符.光束质量接近衍射极限.目前装置可工作于9-11μm.     

Novel Phenomenon of Oxygen-to-oxygen Silyl Migration in Directed Aldol Reaction

The phenomenon of migration of the silyl groups from α-oxygen to β-oxygen in sodium aldol reaction was observed for the first time in this paper.     

Methanol synthesis from CO2: a DFT investigation on Zn-promoted Cu catalyst

Research on Chemical Intermediates - The reaction steps during methanol synthesis from CO2/H2 are influenced by the type of catalysts such as pure Cu and Zn-decorated Cu. In this study, density...     

AN ALGORITHM FOR JORDAN CANONICAL FORM OF A QUATERNION MATRIX

In this paper, we first introduce a concept of companion vector, and study the Jordan canonical forms of quaternion matrices by using the methods of complex rep resentation and companion vector, not only give out a practical algorithm for Jordan canonical form J of a quaternion matrix A, but also provide a practical algorithm for corresponding nonsingular matrix P with P-1AP = J.     

Improved Visible-light Photocatalytic Properties of ZnFe2O4 Synthesized via Sol-gel Method Combined with a Microwave Treatment

ZnFe₂O₄(ZFO) was synthesized via a sol-gel method firstly, then the ZFO was irradiated with microwave treatment to obtain M-ZFO using NH₄Cl as dispersant for 10 min to improve the photocatalytic activity. Large particles of ZFO were broken into small and uniform particles by the gases of hydrogen chlorine and ammonia during the decomposition of NH₄Cl. Compared to ZnFe₂O₄ without microwave treatment(ZFO), M-ZFO exhibits smaller particle size, higher surface area and larger saturation magnetization. More importantly, the photocatalytic activity of M-ZFO for methylene blue was increased by 25% compared with that of ZFO.     

石墨烯在无机材料中的闪光

石墨烯作为一种新晋的无机材料,受到了科学界和工业界的广泛关注。本文就石墨烯出现的历程、结构特点、物理性质和载体作用展开简明的介绍,结合石墨烯在化学、生物等领域应用的实例,详细阐述石墨烯在科研与生活中的应用。最后,总结了石墨烯应用面临的挑战。     

Iron(III)‐Quantity‐Dependent Aggregation–Dispersion Conversion of Functionalized Gold Nanoparticles

Developing gold nanoparticles (AuNPs) with well‐designed functionality is highly desirable for boosting the performance and versatility of inorganic–organic hybrid materials. In an attempt to achieve ion recognition with specific signal expressions, we present here 4‐piperazinyl‐1,8‐naphthalimide‐functionalized AuNPs for the realization of quantitative recognition of Fe^III ions with dual (colorimetric and fluorescent) output. The research takes advantage of 1) quantity‐controlled chelation‐mode transformation of the piperazinyl moiety on the AuNPs towards Fe^III, thereby resulting in an aggregation–dispersion conversion of the AuNPs in solution, and 2) photoinduced electron transfer of a naphthaimide fluorophore on the AuNPs, thus leading to reversible absorption and emission changes. The functional AuNPs are also responsive to pH variations. This strategy for realizing the aggregation–dispersion conversion of AuNPs with returnable signal output might exhibit application potential for advanced nanoscale chemosensors.     

Novel Access to Organostannane Compounds under Ultrasound Irradiation

A simple and efficient procedure has been developed for the synthesis of organostannane compounds by one-pot reaction of stannane halides, magnesium turnings and organic halides in the presence of 1,2-dibromoethane under ultrasound irradiation.     

酸性氧化电位水制备的影响因素

对酸性氧化电位水的产生条件进行单因素分析的结果表明,在实验研究范围内电解质浓度越高、电压越大、极间距越小、电解时间越长,酸性氧化电位水的水质越好.考虑到制水成本和效率,制备酸性氧化电位水的最佳反应参数为:CNaCl=1.5～2.5g/L,U=15～20V,d=20～30mm,t=2～4min.