化学研究中的扫描探针显微学

20世纪 80年代初期 ,扫描隧道显微技术 (ＳｃａｎｎｉｎｇＴｕｎｎｅｌｉｎｇＭｉｃｒｏｓｃｏｐｙ,以下略称为ＳＴＭ)问世[1] 。以后仅十余年 ,以ＳＴＭ为代表的扫描探针显微技术 (ＳｃａｎｎｉｎｇＰｒｏｂｅＭｉｃｒｏｓｃｏｐｙ,ＳＰＭ)迅速发展 ,应用也已经拓展到了包括物理、化学、生物、材料等众多领域。可以预言 ,随着科学技术的不断进步 ,ＳＰＭ技术将不断显示出其优越性 ,尤其在纳米科技异军突起的今天 ,越发离不开这一集观察、分析及操作原子分子等功能于一体的技术。本文我们将着重介绍ＳＰＭ技术 ,特别是电化学ＳＴＭ技术在化…     

稳定自由基存在下苯乙烯聚合的加速剂

研究了稳定自由基存在下苯乙烯的活性聚合,发现在β－酮酸酯－乙酰乙酸乙酯,乙二酸二乙酯,1,3－二酮－乙酰丙酮的少量存在下,苯乙烯聚合速率显著增加,分子量可控,分子量在布较窄。而乙酰丙酮较大量存在下,聚苯乙烯分散性稍微变宽。     

2-羟基-1O,11-二氢-5H-二苯并[a,d]环庚烯-5-酮的合成

以2－羟基苯甲醛和3－甲氧基苯乙酸为原料,经3步反应合成2－羟基－10,11－二氢－5H－二苯并[a,d]环庚烯－5－酮。     

Fe-Al-Mg-MMH/钠质蒙脱土分散体系触变性研究

研究了Fe-Al-Mg型混合金属氢氧化物(简称MMH)/钠质蒙脱土(简称MT)分散体系的触变性,发现在不同MMH/MT质量比(R)条件下,分散体系可分别呈现正触变性和负触变性.在所研究的R范围(0～0.091)内,随R增大,体系的触变性发生正触变性-复合触变性-负触变性的转化.考察了高速剪切分散后,测定粘度变化前的静置时间(ts)和测定粘度时的剪切速率(DL)对触变性的影响.探讨了各种触变性产生的原因,提出了“分散粒子-空间连续网络结构-密实聚集体”和“分散粒子-密实聚集体-密实聚集体簇”机理,较合理地解释了观察到的复合触变现象.     

Rh/SiO_2催化剂上甲烷部分氧化制合成气反应机理的研究(英文)

运用ＴＰＳＲ、ＴＲ－ＦＴＩＲ和化学捕获技术（ＣＨ３Ｉ作捕获剂）,探讨了Ｒｈ／ＳｉＯ２催化剂上的ＰＯＭ反应机理,由此提出热分解氧化机理,认为ＣＨｘ（ｘ＝１～３）和ＣＨｘＯ（ｘ＝１～３）可能是反应物种。     

Chains of (4,4′‐bipyridyl)copper(I) bridged by dimolybdate units

The crystal structure of the title compound, poly­[bis‐[copper(I)‐μ‐(4,4′‐bipyridyl)‐N:N′]‐μ‐dimolybdato‐O:O′],[Cu₂(C₁₀H₈N₂)₂{Mo₂O₇}]_n, consists of {Mo₂O₇}^2? units (with the central O atom lying on twofold symmetry axes) and [Cu(4,4′‐bipy)]_nⁿ⁺ chains (bipy = bipyridyl); the chains are generated by a c‐glide‐plane operation. The {Mo₂O₇}^2? units are covalently bridged to two [Cu(4,4′‐bipy)]_nⁿ⁺ chains, forming a complex with a bridged double‐chain structure. The Cu—O and Cu—N distances are 2.191 (3) and 1.933 (3) Å, respectively.     

A hydrated ethyl­ene­di­ammonium salt of a new polymeric polyoxoanion: (H2en)4[Co(H2O)2(OH)2(VO)6(HPO4)4(PO4)4]·3H2O

The title compound, tetrakis­(ethyl­enedi­ammonium) tetra‐μ‐hydrogenphosphato‐di‐μ‐hydro­xo‐ tetra‐μ‐phosphato‐bis­(aqua­cobalt)­hexakis­(oxovanadium) trihydrate, was synthesized hydro­thermally at moderate temperature. The structure consists of diprotonated ethyl­enedi­ammonium cations and layers of the polyanions. The polyanion contains four PO₄ tetrahedra and three VO₅ square pyramids that are linked through corner‐sharing by alternating P—O—V, which gives rise to a chain. The chains, connected by CoO₄(H₂O)₂ octahedra, form layers, resulting in a two‐dimensional layered structure. The Co—O distances are in the range 1.984 (3)–2.038 (4) Å, the P—O distances 1.508 (3)–1.575 (3) Å and the V—O distances 1.585 (3)–2.010 (3) Å.     

Controllable cubic and hexagonal GaN growth on GaAs(0 0 1) substrates by molecular beam epitaxy

Two kinds of GaN samples were grown on GaAs(0 0 1) substrates. One is grown on nitridized GaAs surface, the other is grown on nitridized AlAs buffer GaAs substrate. X-ray diffraction and photoluminescence measurements find that the GaN sample directly grown on GaAs substrate is pure cubic phase and those grown on AlAs buffer is pure hexagonal phase. The present study shows that the phase of GaN samples grown on GaAs substrates can be controlled using different buffer layers.     

三维接触问题的非光滑算法

给出了一种非光滑算法直接用于求解三维摩擦接触问题的不可微非线性互补模型,不再对模型进行光滑化处理,使算法更加简单。文中对非光滑算法的收敛性给出了严格的数学证明,数值实验表明该算法列式简单,但与光滑化算法同样有效。     

固液萃取分离分光光度法测定痕量锰(Ⅱ)的研究

描述了石蜡萃取分光光度测定痕量锰过程.在pH=8.5～10.0范围内,锰和1-(2-吡啶偶氮)-2-萘酚显色络合物能定量被石蜡萃取,将萃取的固相体系溶解在CHCl3中,在λ=570 nm处进行光度测定.锰量在0～10 μg/10 mL范围内符合比耳定律,线性回归方程为y=0.003 2+0.0486 x.方法应用于实际样品中痕量锰测定,结果良好.