Binding mechanisms of methacrylic acid and methyl methacrylate on si(111)-7 x 7 -- effect of substitution groups

The interaction of methacrylic acid and methyl methacrylate with Si(111)-7 x 7 has been investigated using high-resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS). While methacrylic acid chemisorbs dissociatively through O-H bond cleavage, methyl methacrylate is covalently attached to the silicon surface via a [4+2] cycloaddition. The different reaction pathways of these two compounds on Si(111)-7 x 7 demonstrate that the substitution groups play an important role in determining the reaction channels for multifunctional molecules, leading to the desired flexibility in the organic modification of silicon surfaces.     

烷基磷（膦）酸萃取剂钠盐与非离子表面活性剂AEO_9混合体系胶团的形成和分子间的相互作用

本文研究了烷基磷（膦）酸萃取剂钠盐ＮａＥＨＥＨＰ，ＮａＤＴＭＰＰ，Ｎａ_２（ＭＥＨＰ）与非离子表面活性剂ＡＥＯ_９以不同比例复配后水溶液胶团的形成及分子间的相互作用，结果表明混合胶团的形成使ＣＭＣ大大降低。分子间在胶团中的相互作用强弱为：Ｎａ_２（ＭＥＨＰ）体系＞ＮａＤＴＭＰＰ体系＞ＮａＥＨＥＨＰ体系，分子间在表面层的吸引作用小于同体系分子间在胶团中的相互作用，这一结果有利于混合胶团的形成。     

Dry synthesis of triple cumulative double bonds (C=C=C=N) on Si(111)-7 x 7 surfaces

The interactions of cyanoacetylene and diacetylene with a Si(111)-7 x 7 surface have been studied as model systems to mechanistically understand the chemical binding of unsaturated organic molecules to diradical-like silicon dangling bonds. Vibrational studies show that cyanoacetylene mainly binds to the surface through a diradical reaction involving both cyano and C[triple bond]C groups with an adjacent adatom-rest atom pair at 110 K, resulting in an intermediate containing triple cumulative double bonds (C=C=C=N). On the other hand, diacetylene was shown to the covalently attached to Si(111)-7 x 7 only through one of its C[triple bond]C groups, forming an enynic-like structure with a C=C-C[triple bond]C skeleton. These chemisorbed species containing triple cumulative double bonds (C=C=C=N) and C=C-C[triple bond]C may be employed as precursors (or templates) for further construction of bilayer organic films on the semiconductor surfaces.     

A [4+2]-like cycloaddition of methyl methacrylate on Si(100)-2 x 1

The attachment of methyl methacrylate (MMA) on Si(100)-2x1 was investigated using high-resolution electron energy loss spectroscopy (HREELS), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and density functional theory (DFT) calculations. The HREELS spectra of chemisorbed MMA show the disappearance of characteristic vibrations of C=O (1725 cm(-1)) and C(sp(2))-H (3110, 1400, and 962 cm(-1)) coupled with the blue shift of the C=C stretching mode by 34 cm(-1) compared to those of physisorbed molecules. These results clearly demonstrate that both C=C and C=O in MMA directly participate in the interaction with the surface to form a SiCH(2)C(CH(3))=C(OCH(3))OSi species via a [4+2]-like cycloaddition. This binding configuration was further supported by XPS, UPS, and DFT studies.     

Ni2L配合物的热稳定性和电化学研究

用金属离子作模板通过N－氧化吡啶－2，6－二甲醛与1，3－丙二胺缩合得到了新型大环水溶性希夫碱金属配合物Ni2LCl6·C2H5OH·10H2O，对其进行了元素分析、红外光谱、电化学及热稳定性能的研究．结果显示：Ni2L配合物的电极反应可以认为是一个双电子传输过程，并且电极过程是一个不可逆过程，求得它的扩散系数为4．07×10－6cm2·s-1．该配合物的稳定性较好，约在563℃配合物发生分解，失去有机基因，生成氧化物．     

Bridging nanogap electrodes by in situ electropolymerization of a bis(terthiophenylphenanthroline)ruthenium complex

A novel complex containing a 3,8-bis[terthiophenyl-(1,10-phenanthroline)] ligand coordinated to [Ru(bpy)(2)] was synthesized and characterized by electrochemical and spectroscopic techniques. The complex was shown to be a suitable starting material for the electrodeposition of functionalized molecular wires between nanogap electrodes to generate stable molecular nanodevices. Temperature-dependent nonlinear I-V curves were obtained at 80-300 K. The material can also be deposited on indium tin oxide (ITO) to form compact electrochromic films at surface concentrations lower than approximately 1 x 10(-8) mol cm(2); however, a more loosely bond fibrous form is preferentially deposited at higher surface concentrations.     

L-Shell X-Ray Production Cross Sections of Ta and Tm by Electron Impact near the Threshold Region

We present experimental measurements of L-shell production cross sections Lα, Lβ and Lγ for tantalum and thulium by electron impact at incident electron energies from about one to three times the threshold energy. From the experimental data, the total production cross section and mean ionization cross section are deduced. The influence of electrons reflected from the substrate is corrected by the electron transport bipartition model. Tile measured cross sections are compared with the theoretical predictions.     

Analytic calculation of magnetic force between two current-carrying coils

Current-carrying coils are basic elements in electromagnetic equipments, for example, in high field magnets from high temperature superconducting wires or tapes. In the assembly of these systems and their current-carrying operation, unavoidable mis-alignment and shift from the original position can be induced by disturbances such as the imbalance of magnetic force due to safety problems. For two current-carrying coils with non-coplanar axes, the analytic expression of the magnetic force between the two coils is presented according to the rule of Ampere circulation and the Biot-Savart law. Based on the expression, the dependence of the magnetic force on the size and the relative position of each other is further investigated, and the variation of the magnetic force is obtained with the above parameters.