The Influence of an Acid-base-equilibrium on the Adsorption Behaviour of a Weak Polyampholyte

A weak diblock polyampholyte PMAA-b-PDMAEMA, poly(methacrylic acid)-block-poly((dimethylamino)ethyl methacrylate), was investigated as a model system for the influence of an acid-base-equilibrium of a phthalic acid buffer system on the polyelectrolyte adsorption behaviour. The adsorption of polyampholyte from aqueous solution onto silicon surfaces is known to be strongly influenced by the parameters of the polymer solution and the properties of the polyampholyte itself like block ratio or molecular weight. In the case of the investigated polyampholytes, the main parameter with the most significant influence on the adsorption is the pH. The big influence of pH on adsorption results from the charges of the polymer chains and the substrate, which are determined by the pH. Therefore, it should be useful to investigate the influence of a buffer system on the polyampholyte adsorption. On the one hand the buffer system enables to determine the pH of the aqueous polyampholyte solution more precisely. On the other hand the concentrations of different phthalic species like the phthalic acid, the hydrogen phthalate and the phthalate are strongly influenced by pH. These different species were observed to have a strong influence on the adsorption behaviour of the polyampholyte, so the adsorption as function of pH was observed to be also determined by the acid-base-equilibrium of the buffer system. The adsorbed amount of polyampholyte dried after the adsorption process was determined using ellipsometry, while the surface topography of these adsorbed layers were characterized by atomic force microscopy (AFM). This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and characterization of aspartate polymer complexes

Oligomeric polyester, namely poly(tetramethylene asparate) (PTMA), was synthesized From D ,L ‐aspartic acid and 1,4‐butanediol by a melt codensation technique. Polyester–metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Fe(III), Pd(IV), and UO₂(II) in DMSO. The polyester–metal complexes were characterized by elemental analysis, UV–Vis, IR spectral studies, magnetic susceptibility measurements and ¹H‐NMR. Mossbauer spectra of mixed samples of Pd‐PTMA and Fe(II)‐PTMA with a ratio of 1 : 2 mol showed the iron(III) oxide formed in early stages of the decomposition at 250°C is mainly fine‐grained and as the temperature is increased, well‐crystalline hematic is formed. Above 250°C, the Mossbauer spectrum showed the typical six‐line pattern of magnetically oriented Fe(III) oxide, but at 800°C, the spectrum showed quadrupole interaction characteristic of PdFe₂O₄ spinel. The metal ions were found to be six—coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (DTA‐TG) showed that co‐ordination polymers are thermally more stable than polyester; the activation parameters for both decomposition steps were calculated and discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 942–947, 2004     

取代基效应对锇(Ⅱ)羟基喹啉配合物结构和光谱性质的影响

从理论上研究了一系列[Os(CO)3(tfa)(O^N)](tfa=三氟乙酸;O^N=5-氟-羟基喹啉(1),羟基喹啉(2)和2:甲基-羟基喹啉(3))配合物的结构和光谱特征.分别采用B3LYP/LANL2DZ和CIS/LANL2DZ方法优化了它们的基态和激发态结构.计算得到的Os-C、Os-N和Os-O基态键长和相应...     

Microinfrared reflection spectroscopic mapping: application to the detection of hydrogen-related species in natural quartz

A new method of microinfrared reflection spectroscopy and mapping analysis is briefly introduced. It was used to detect distributions and structures of hydrogen‐related species (e.g. H₂O, SiOH and SiH) in plastically deformed natural quartz. We used a Fourier transform‐infrared spectrometer with a microscopic imaging system fully automated for all microscope functions (e.g. focusing, aperture, stage motion and measurements). Mapping can be made in thin sections with a thickness of 50 µm at room temperature and low temperatures (77 K) using a liquid N₂ cooling system. Infrared reflection spectra were obtained by five scans for each point with a range from 4000 to 400 cm^?1. The spectra were measured five times within about 2.5 s at each position. The scanning interval was 100–150 µm using a 100 × 100 µm² aperture. All obtained spectral data were stored in computer memory to construct two‐dimensional mappings of infrared absorption. From the comparisons between infrared mapping images and deformation microstructures, in addition to the molecular H₂O around 3600–3400 cm^?1, the hydrogen‐related point defects (i.e. SiOH and SiH) around 970–900 cm^?1 within quartz grains and between grain boundaries increased with decreasing grain sizes (increasing plastic strain). The method can detect the SiOH and SiH along grain boundaries that enhance the hydrolytic weakening of natural quartz.     

高压退火气氛对溶液法制备a-IGZO薄膜光学特性的影响

利用椭圆偏振光谱仪和原子力显微镜,研究了相同温度下不同退火气氛及压强处理对溶液旋涂法制备a-IGZO光学特性和薄膜微观结构的影响。实验结果表明,当退火气氛为O₂时,压强由0.1 MPa增加到1.5 MPa,薄膜的光学带隙由3.23 eV增大到3.31 eV,表面粗糙层由6.77 nm降低到4.77 nm。与N₂气氛相比,1.5 MPa O₂气氛下薄膜的光学带隙有所提高,表面粗糙度也有所降低。因此,在1.5 MPa O₂气氛下,可以有效降低薄膜内部有机物的残留及缺陷,形成更加致密的非晶a-IGZO薄膜。     

Structural and spectroscopic properties of some neodymium-boro-germanate glasses and glass ceramics embedded with silver nanoparticles

Neodymium-boro-germanate glasses and glass ceramics (with Nd₂O₃ contents up to 40 mol%) embedded with silver metallic nanoparticles (AgNPs) were prepared by the melt-quenching technique. Two series of samples (with AgNPs and without AgNPs) were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance ultraviolet–visible (DR-UV–vis) spectroscopy and photoluminescence (PL) spectroscopy. XRD data reveal that for both series the samples with x < 40 mol% Nd₂O₃ are basically amorphous containing only small amounts of a crystalline phase (identified as crystalline B₂O₃) while for samples x = 40 mol% Nd₂O₃ an important amount of a crystalline phase (identified as the NdBO₃ orthorhombic phase) is present. FT-IR spectroscopy data show that addition of controlled amounts of Nd₂O₃ and AgNPs changes the structural units that build up the host glass ceramic network. These changes were confirmed also by the photoluminescence spectra that show that addition of AgNPs to the host matrix produces changes at the level of emission peaks. The positive values of bonding parameter (δ) calculated based on DR-UV–vis data indicate a covalent character of the bonds from the studied samples.     

Broadband 1.53 μm emission in Er-doped Ga-Bi-Pb-Ge heavy metal oxide glasses

We investigated the thermal stability and spectroscopic properties of the 1.53 μm emission from ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ ions in Er³⁺/Yb³⁺-codoped Ga-Bi-Pb-Ge heavy metal oxide glass for use in broadband fiber amplifiers. It was noted that the addition of GeO₂ effectively enhanced the thermal stability of the heavy metal oxide glass studied. The emission peak located at approximately 1530 nm with a full width at half-maximum of approximately 58 nm. The measured lifetime and the calculated emission cross-section of this transition were 3.2 ms and 10.3×10⁻²¹ cm², respectively. As a result, Ga-Bi-Pb-Ge heavy metal oxide glasses were assumed to be potential host material for the 1.53 μm broadband optical fiber amplifiers.     

Growth mechanisms and their effects on the opto-electrical properties of CdS thin films prepared by chemical bath deposition

Chemically deposited CdS exhibits high sensitivity in the opto-electrical performance to the growth mechanisms. Hence it is of a great interest to study the effects of growth mechanisms on the opto-electrical performance in such films. Studies were carried out by the means of spectroscopic ellipsometry, and coupled with structural, optical, and electrical characterization. A range of bath temperatures (55 °C–95  °C) were used as the means to alter the growth mechanisms. Ion-by-ion process dominated deposition at lower bath temperatures throughout the length of the deposition. This mechanism produced films composed of single phase cubic crystals with corresponding opto-electrical properties inherent to such structures. Complex formations at higher bath temperatures supplement the sole ion-by-ion mechanisms with the cluster-by-cluster mechanism. This results in a mixed cubic/hexagonal structure, and deviation from stoichiometry. As a result, carrier concentrations and mobility increased nearly eight and four fold respectively. Resistivity decreased more than four times from 33.2 to 7.5 Ω cm. A noticeable decrease of, ~0.2 was observed in the refractive index and an increase of ~0.07 eV in the band gap is also reported. Nuclear magnetic resonance analysis confirms deviation from stoichiometry in the cluster-by-cluster mechanisms, resulting in interstitially trapped Cd⁺² and S⁻² ions. The trapped ions act as donors in the film enhancing its electrical performance.     

用磷钼酸喹啉重量法测定化学镀Ni-P镀层中的磷含量

介绍了磷钼酸喹啉重量法在化学镀镍磷镀层磷含量测定中的应用,并与GB/T 13913-92分光光度法和X射线能谱(EDS)法进行了比较.结果表明,本方法测定相对误差为-1.65%～4.21%,能准确测定镍磷镀层磷含量;与EDS法对Ni-P镀层的对比测定表明,EDS法所测结果比重量法普遍偏高.     

光谱分析数据采集与传输网络

介绍了基于ＷｉｎｄｏｗｓＮＴ网络和专用数据传输接口设备的光谱分析数据采集与传输网络,以及相应的软件和硬件设计方案;建立了一套临线和在线分析的数据采集、存储与传输的通用的新方法。解决了光谱仪串口数据格式的自动识别和工业环境下数据传输设备的抗干扰问题。专门设计的数据传输接口设备的传输距离可达３０００ｍ,端口数目可达３０个。采用星型网络拓扑结构,１０／１００ＢａｓｅＴＵＴＰ线缆连接,提供远程拨入和Ｉｎｔｅｒｎｅｔ连接,因此能够提供远程数据管理、远程系统维护以及基于局域网和Ｉｎｔｅｒｎｅｔ的二次开发和应用。结合工艺参数管理软件,不仅能够实现分析数据的现场显示,还能实现炼钢过程中合金化调整的加料计算和投料控制,从而实现冶炼过程的临界控制