Electrochemical and Adsorption Studies on the Formation of Poly-8-Hydroxyquinaldine Thin Films at Glassy Carbon/Electrolyte Interface

The kinetics and thermodynamics of the electropolymerization of the chelating agent 8-hydroxyquinaldine on GCE's (Glassy Carbon Electrodes') surface from aqueous phosphate buffers are reported. Thermodynamic functions related to the adsorption of the monomer on the GCE's surfaces were determinated. No contribution from GCE surface's functional group to the electropolymerization reactions was reported. The effects of monomer concentration, pH, and temperature on the electrochemical growth of poly 8-hydroxyquinaldine were investigated. The results suggest that the propagation of the electropolymerization process takes place via a free radical chain reactions. Furthermore, the results indicate that the electrochemical growth of the polymeric films is dictated by pre-polymerization adsorption on the electrode surface.     

Electrochemical Studies of Polymeric Carbons. II. Surface Layer Formation on Glassy Carbon Electrodes in Chloride Solutions as Studied by Radiotracer Techniques

The interaction of chloride ions with glassy carbon electrodes is studied by means of ³⁶Cl as radiotracer. Chloride ions are bonded on the electrode in case of anodization depending on electrode potential and duration of the polarization. Strong interaction is observed at electrode potentials more positive than +1.3 V. A significant part of the chloride ions bonded at the glassy carbon can not be displaced neither by cathodic polarization nor by rinsing with water or non-labelled solutions. It is concluded that chloride ions are chemically bonded at the surface and the surface region of glassy carbon.     

FTIR法研究BCN薄膜的内应力

采用射频磁控溅射技术,用六角氮化硼和石墨为溅射靶,以氩气(Ar)和氮气(N₂)为工作气体,在Si(100)衬底上制备出硼碳氮(BCN)薄膜。利用傅里叶变换红外光谱(FTIR)考察了不同沉积参数(溅射功率为80～130 W、衬底温度为300～500 ℃、沉积时间为1～4 h)条件下制备的薄膜样品。实验结果表明,所制备薄膜均实现了原子级化合。并且沉积参数对BCN薄膜的生长和内应力有很大影响,适当改变沉积参数能有效释放BCN薄膜的内应力。在固定其他条件只改变一个沉积参数的情况下,得到制备具有较小内应力的硼碳氮薄膜的最佳沉积条件：溅射功率为80 W、衬底温度为400 ℃、沉积时间为2 h。     

紫外光下纳米TiO2薄膜亲水性机理的电化学研究

利用溶胶 凝胶方法在透明导电玻璃ITO (SnO2 ∶In)表面制备纳米TiO2 薄膜 ,XRD谱图表明TiO2 是锐钛矿晶型 ,AFM (Atomic Force Microscope)测得薄膜表面粒子约为 10 0nm .研究了ITO表面纳米TiO2 薄膜的光致亲水性变化 .通过循环伏安技术测定TiO2 薄膜电极在 2 5 3.7nm的紫外光照射后的电化学行为推测光致亲水性机理 .发现在紫外光照射一定时间后 ,TiO2 薄膜电极的循环伏安图在 +0 .0 35V处出现新的氧化峰 ;且随光照时间的增加 ,氧化峰的峰电流增大 ,溶液中的溶解氧对峰电流的大小有明显影响 .实验表明 ,在紫外光照下电极表面有Ti3 + 产生 ,证实了TiO2 薄膜的光致亲水性转变过程与Ti3 + 的生成导致的表面结构变化有关     

Effect of Terraces at the Interface on the Structural and Physical Properties of La_(0.8)Sr_(0.2)MnO_3 Thin Films

Employing atomic force microscopy,transmission electron microscopy and the second harmonic generation technique,we carefully explore the structural properties of 6-unit-cell-thick La_(0.8)Sr_(0.2)MnO_3 films grown on SrTiO_3 with atomically flat TiO_2-terminated terraces on the surface.The results clearly demonstrate that the terraces on the surface of TiO_2-terminated SrTiO_3 can improve the layer-by-layer epitaxial growth of the manganite films,which results in uniform film coverage at the beginning of growth and thus reduces the substrate-induced disorder at or near the interface.Comparing the magnetic and transport properties of La_(0.8)Sr_(0.2)MnO_3 films with the thicknesses varying from 6 unit cells to 80 unit cells grown respectively on as-received SrTiO_3 and TiO_2-terminated SrTiO_3,it is found that these atomically flat terraces on the surface of TiO_2-terminated SrTiO_3 can greatly enhance the Curie temperature and conductivities of the ultrathin La_(0.8)Sr_(0.2)MnO_3 films with thickness less than 50 unit cells,while no obvious difference is detected in the magnetic and transport properties of the 80unit-cell thick films.     

柔性ITO衬底电化学沉积制备Cu/Cu2O薄膜

研究了使用电化学沉积法于碱性条件下在柔性ITO衬底上制备Cu/Cu₂O薄膜的方法。循环伏安曲线表明Cu₂O与Cu的阴极峰分别位于-500 mV(vs Ag/AgCl)和-800 mV(vs Ag/AgCl)附近。利用循环伏安法考察了生长温度和电解液pH值等对Cu₂O与Cu阴极峰电位的影响,阴极峰随生长温度的升高以及pH值的降低而略向阳极移动,沉积电流也随之相应增大。与弱酸性条件相比,上述两个阴极峰随pH值升高而移动的程度明显减小,这可能与碱性条件下C₃H₆O电离程度增大以及C₃H₆O根作为配体的过量程度有关。通过X射线衍射光谱和扫描电子显微镜的表征证实,在所研究的生长温度区间和pH值内可利用电化学沉积法在柔性ITO衬底上制备Cu/Cu₂O纳米混晶薄膜。在相同的生长温度和pH条件下,电化学沉积电位对样品表面形貌和晶体性质具有较大影响。     

Al(111)/Al_3Li(111)的界面性质

运用基于第一性原理的平面波贋势法,计算研究了Al (111)/Al_3Li (111)的界面性质.结果表明:Al (111)/Al_3Li (111)的界面具有三种原子配位关系结构,其中界面处仍保持与基体Al一致的三明治堆垛构型的界面稳定性最好.计算表明,该结构界面最薄弱层,位于Al_3Li (111)内,其分离功最小(约1.53 J/m~2),强度最弱,而基体Al和Al_3Li内部的强度随着到界面距离的增大而逐渐增强.     

Electronic States and Schottky Barrier Height at Metal/MgO(100) Interfaces

Using an ab initio total energy approach, we study the electronic structure of metal/MgO(100) interfaces. By considering simple and transition metals, different adsorption sites and different interface separations, we analyze the influence of the character of metal and of the detailed interfacial atomic structure. We calculate the interface density of states, electron transfer, electric dipole, and the Schottky barrier height. We characterize three types of electronic states: states due to chemical bonding which appear at well defined energies, conventional metal-induced gap states associated to a smooth density of states in the MgO gap region, and metal band distortions due to polarization by the electrostatic field of the ionic substrate. We point out that, with respect to the extended Schottky limit, the interface formation yields an electric dipole mainly determined by the substrate characteristics. Indeed, the metal-dependent contributions (interfacial states and electron transfer) remain small with respect to the metal polarization induced by the substrate electrostatic field.     

Room-Temperature Ferromagnetism of Co-Doped CeO2 Thin Films on Si（111） substrates

Using Co2O3 as the Co source, doped cerium oxide thin films with the composition of Ce0.97C00.03O2-δ （CCO） are deposited on Si（111） and glass substrates by pulse laser deposition technique. X-ray diffraction reveals that CCO films with （111） preferential orientation are grown on Si, while the fihn on glass is polycrystalline with nanocrystal. X-ray photoelectron spectroscopy shows that the （Jo displaces the （;e atom and exists in high spin state rather than low spin state, which contributes to the room-temperature ferromagnetism confirmed by vibration sample magnetometer. I~ilms on Si and glass are different in ferromagnetism, which is believed to be induced by different film microstructures. Based on these results, the possible ferromagnetism in this insulating film is discussed. Anyway, successful fabrication of CCO films with room-temperature ferromagnetism on Si substrates is of great importance in both technological and theoretical aspects.     

Cooperative Association of p-Alkylbenzene Sulfonates Sodium Salts to Poly-2-(dimethylamino) Ethylmethacrylate-N-alkyl Quaternized at the Water/Chloroform Interface

The association of p-alkyl benzene sulfonate sodium salts with several poly-2-(dimethylamino) ethylmethacrylate-N-alkyl quaternized bromides at the water/chloroform interface was studied. High association percentages were found which increase with both the size of the sulfonate molecule and the length of the polyelectrolyte side chain: octyl, decyl, dodecyl and tetradecyl. The results fit well to the Hill's equation for the association of anionic surfactant to polyelectrolytes. Benzene sulfonate shows an anticooperative behavior for the association, whereas 4-methyl benzene sulfonate and 4-ethylbenzene sulfonate are increasingly cooperative for the association. From the association constants, the standard free energies of transfer from water to the interfacial polyelectrolytes were determined. Their values were a linear function of the number of carbon atoms of the aliphatic residue of the benzene sulfonate molecule ranging from ?15.7 kJ/mol of CH₂ groups for the octyl polyelectrolyte to ?18.9 kJ/mol of CH₂ groups for the tetradecyl derivative. These values are similar to those reported for the association of some of these sulfonates molecules with ammonium type cationic micelles. The results for the incremental free energy of transfer by mol of methylene group from water to micelles are in the same order of magnitude as those reported for p-alkyl phenoxides and p-alkylbenzoates to hexadecyltrimethyl ammonium bromide micelles. The results shows that amphipathic counterions as small as 4-ethylbenzenesulfonate are enough to induce a cooperative effect in their association to cationic polyelectrolytes.     

Photoacoust1C Studies on Very Thin Poly(Methyl Methacrylate) Films Prepared by a Cast1Ng-On-Water Method

Photoacoustic (PA) responses from very-thin poly(methyl methacrylate) (PMMA) films were investigated at various lamination conditions. The PA signal increased when the dye-doped films were laminated up to five layers, but tended to saturate beyond five layers. When the blank films were superimposed on the dye-doped film, the signal became smaller. The signal was larger when the dye-doped film was arranged outermost in the laminated film assembly of dye-doped and blank films. The results imply the effect of film vibration on the PA response.     

PTCDA/ITO表面和界面的X射线光电子能谱分析

利用X射线光电子能谱对PTCDA/p-Si有机/无机光电探测器中PTCDA/ITO表面和界面进行了测试分析。结果表明,苝环上的C原子的结合能为284.6 eV,酸酐中的C原子的结合能为288.7 eV,并存在来源于ITO膜中的氧对C原子的氧化现象,界面处C(1s)谱中较高结合能峰消失,且峰值向低结合能发生化学位移;CO键中O原子的结合能为531.5 eV,C—O—C键中的O原子的结合能为533.4 eV。     

Atomic Design of Polarity of GaN Films Grown on SiC(0001)

Ab initio total energy calculations are used to determine the interface structure of GaN films grown on 6H-SiC(0001) with different substrate reconstructions. The results indicate that GaN films grown on bare SiC(0001) are of the Ga-polarity, while GaN films grown on SiC(0001) with Si adlayer are of the N-polarity if there is no N-Si interchange at the interface. With the interchange, the GaN films are of the Ga-polarity.     

n型InP(100)衬底上电沉积氧化锌薄膜的

采用电化学沉积方法在n型InP(100)(1016)衬底上制备了氧化锌薄膜。探索线性扫描伏安法确定InP与0.1mol/LZn(NO3)2电解液的体系中沉积氧化锌的极化电势,在20℃溶液中,相对于甘汞电极(SCE)的极化电势为-1.1877V。扫描电镜照片显示:随着应用电势的降低,氧化锌薄膜变得紧密平滑;狭窄的X射线衍射峰也说明低电势下薄膜的结晶质量较好。光荧光表征发现低电势下制备的氧化锌薄膜具有良好的发光特性。     

First Principles Study of Half Metallic Properties of VSb Surface and VSb/GaSb (001) Interface

The structural, electronic, and magnetic properties of VSb in zincblende, andNiAs phases, VSb (001) film surfaces and its interfaces with GaSb (001) havebeen investigated within the framework of the density functional theoryusing the FPLAPW+lo approach. The NiAs structure is more stable than the ZB phase, ZB VSb is found to a half-metallic ferromagnetic. The V-terminated surfaces retain the half-metallic character, while the half-metallicity is destroyed for Sb-terminated surfaces due to surface states, which originate from p electrons. The phase diagram obtained through the ab-initio atomisticthermodynamics shows that the formation energy of ZB VSb is about 0.1 Ryd.The half-metallicity character is also preserved at VSb/GaSb (001) interface.The conduction band minimum (CBM) of VSb in the minority spin case liesabout 0.47 eV above that of GaSb, suggesting that the majority spin can beinjected into GaSb without being flipped to the conduction bands of the minority spin.     

Three Dimensional Branched Gold Nanostructures on Reduced Graphene Oxide Films Formed at a Liquid/Liquid Interface

Interfacing anisotropic gold nanostructures with graphene can open up new avenues for modifying the light–matter interaction of graphene. A chemical route is explored to synthesize branched gold nanostructures on reduced graphene oxide (rGO) layers by in situ reduction, assisted by binary surfactant mixtures containing tetraoctylammonium bromide with cetyltrimethy­lammonium bromide, sodium dodecylsulfate, or sodium citrate. The hybrid material self‐assembles at a liquid/liquid interface forming a free‐standing film. Electron microscopy studies reveal the morphology, microstructure, and crystallinity of the hybrids. The gold nanostructures are branched in three dimensions and possess various shapes, such as irregular stars, multipods, and spiky features, interspersed with rGO layers. The hybrids exhibit plasmon modes in the visible and near‐infrared region due to the shape anisotropy. The enhancement effect of the spiky features is also observed in the Raman spectra. The growth mechanism of the branched nanostructures is followed by kinetic studies and indicates that the formation of multiple twinned crystals is the key factor for branching.     

铜铟镓硒薄膜光伏组件中电池与封装材料界面的光学特性对组件性能的影响

根据测试数据,分析模拟了铜铟镓硒(CIGS)薄膜光伏组件中电池的活性区域、非活性区域与封装材料之间界面的光学特性对组件的短路电流产生的影响。根据组件结构建立了光学模型,从光学模拟结果分析组件内的反射与吸收。发现电池前电极透明导电氧化物薄膜(TCO)与封装材料界面的反射不可忽视,提出通过在透明导电氧化物薄膜与封装材料之间添加减反射层,并以MgO作为膜层材料以降低活性区域的界面反射;模拟了在非活性区域一次反射光角度与二次反射的关系,由此分析了非活性区域反射面倾角、镜面反射与漫反射比例对光利用的影响。模拟结果显示,活性区域的减反层结构可降低透明导电氧化物薄膜表面的反射率1%以上,而通过在非活性面积区域制备光反射结构,理论上能够利用非活性区域光照超过50%。     

三价铕离子配合物的激光光谱研究

利用高灵敏度的时间辨激光光谱技术研究了在配位场作用下Ｅｕ＾３＾＋的直接激发与发特性。Ｅｕ＾３＾＋的直接激发光谱（特别是７Ｆ０－５Ｄ０的超灵敏跃迁）及其发射光谱随不同的配合物的变化，同时观测到与配位对称性及配位强度有联系的７Ｆ１－５Ｄ０磁偶极跃 迁的分裂。在对７Ｆ０－５Ｄ０跃迁共振与非共振的１０ｐｓ激光脉冲的激励下，都可以立即观察到５Ｄ０－７ＦＪ（Ｊ＝２，３，４）的发射，说明Ｅｕ＾３＾＋的５Ｄ０能态     

MnSb/GaSb(001)界面半金属特性的第一性原理研究

利用密度泛函理论计算六角NiAs型和立方闪锌矿型MnSb的电子和电磁特性,研究闪锌矿MnSb与GaSb(001)界面,并采用广义渐变近似计算了交换-相关项．闪锌矿结构的MnSb具有半金属铁磁特性,单分子磁矩4μB,MnSb/GaSb(001)界面同样具有半金属特性．界面中Mn原子的磁矩减小,界面中Sb原子磁矩等于两个相应界面磁矩的平均值．另外计算了能带排列在异质结中价带偏移大约1.25 eV.