Probing the Roughness of Porphyrin Thin Films with X-ray Photoelectron Spectroscopy

Thin-film growth of molecular systems is of interest for many applications, such as for instance organic electronics. In this study, we demonstrate how X-ray photoelectron spectroscopy (XPS) can be used to study the growth behavior of such molecular systems. In XPS, coverages are often calculated assuming a uniform thickness across a surface. This results in an error for rough films, and the magnitude of this error depends on the kinetic energy of the photoelectrons analyzed. We have used this kinetic-energy dependency to estimate the roughnesses of thin porphyrin films grown on rutile TiO₂(110). We used two different molecules: cobalt (II) monocarboxyphenyl-10,15,20-triphenylporphyrin (CoMCTPP), with carboxylic-acid anchor groups, and cobalt (II) tetraphenylporphyrin (CoTPP), without anchor groups. We find CoMCTPP to grow as rough films at room temperature across the studied coverage range, whereas for CoTPP the first two layers remain smooth and even; depositing additional CoTPP results in rough films. Although, XPS is not a common technique for measuring roughness, it is fast and provides information of both roughness and thickness in one measurement.     

Plasma Treatment Enhanced Magnetic Properties in Manganese Doped Titanium Nitride Thin Films

The ferromagnetic manganese doped TiN films were grown by plasma assisted molecular beam epitaxy on MgO(001) substrates. The nitrogen concentration and the ratio of manganese at Ti lattice sites increase after the plasma annealing post treatment. TiN(002) peak shifts toward low angle direction and TiN(111) peak disappears after the post treatment. The lattice expansion and peak shift are mainly ascribed to the reduction of nitrogen vacancies in films. The magnetism was suppressed in as-prepared sample due to the pinning effect of the nitrogen vacancies at defect sites or interface. The magnetism can be activated by the plasma implantation along with nitrogen vacancies reduce. The decrease of nitrogen vacancies leads to the enhancement of ferromagnetism.     

Thin films of mesoporous silica: preparation and characterization

Preparation of mesoporous materials in a thin film geometry was first reported in 1996. Recently, improvement of the preparation methods yielded stable films with well-defined symmetries, controlled pore orientation, continuity and film thickness. The ability to tailor film properties is important for their utilization in applications ranging from catalysis to microelectronics, where morphological control in the meso-domain is vital.     

Transparent Polymer Opal Thin Films with Intense UV Structural Color

We report on shear-ordered polymer photonic crystals demonstrating intense structural color with a photonic bandgap at 270 nm. Our work examines this UV structural color, originating from a low refractive index contrast polymer composite system as a function of the viewing angle. We report extensive characterization of the angle-dependent nature of this color in the form of ‘scattering cones’, which showed strong reflectivity in the 275–315 nm range. The viewing range of the scattering was fully quantified for a number of planes and angles, and we additionally discuss the unique spectral anisotropy observed in these structures. Such films could serve as low-cost UV reflection coatings with applications in photovoltaics due to the fact of their non-photobleaching and robust mechanical behavior in addition to their favorable optical properties.     

Functional Molecular Thin Films: Topological Templates for the Chemoselective Ligation of Antigenic Peptides to Self-Assembled Monolayers

The combination of self-assembly and regioselective surface chemistry has made it possible to immobilize peptide recognition sites 1 on a template attached to a gold surface. Each of the seven individual reaction steps, including the final functional biomolecular recognition, was controlled in situ with surface-sensitive detection techniques. The presented strategy is of general importance for the formation of complex supramolecular structures with biologically interesting functionalities at the interfaces.     

Advanced Surfaces by Anchoring Thin Hydrogel Layers of Functional Polymers

Surface design and engineering is a critical tool to improve the interaction of materials with their surroundings. Immobilization of soft hydrogels is one of the attractive strategies to achieve surface modification. The goal of this review is to provide a comprehensive overview of the different strategies used for surface tethering of hydrogel layers via crosslinking immobilization of pre-fabricated functional polymers. In this strategy, crosslinkable polymers are first prepared via various polymerization techniques or post-functionalization of polymers. Afterwards, the crosslinkable polymers are attached or tethered on the surfaces of substrates using a variety of approaches including photo-crosslinking, click reactions, reversible linkages, etc. For each case, the principles of hydrogel tethering have been explained in detail with representative examples.Moreover, the potential applications of the as-modified substrates in specific cases have also been addressed and overviewed.     

7075铝合金在电解液薄层下的电位波动

在3.5%NaCl电解液膜下,7075铝合金自腐蚀电位随浸泡时间的波动呈如下变化:浸泡初期,自腐蚀电位E波动的幅度极小,继续浸泡至4h后E急剧增大到20mV,而浸泡6h后的波动幅度与腐蚀初期相近,但出现了正向尖峰,至12h后的波动幅度又与4h的相当.实验发现自腐蚀电位的均方差随腐蚀时间呈先负移而后正移的趋势,4h时出现极小值.而电位功率谱密度线性部分的斜率(k),则在4h时呈现较小值,6h时出现最大值.由此推断7075铝合金在薄电解液膜下浸泡6h后其表面产生了稳定的蚀点.     

Metallosupramolecular Thin Polyelectrolyte Films

Molecular recognition and electrostatic interaction of oppositely charged polyelectrolytes are combined in the fabrication of ultrathin metallosupramolecular multilayers [shown schematically in the picture, PEI=polyethyleneimine, PSS=poly(styrene sulfonate)]. The layers between the PSS layers are composed of an iron(II ) bis(terpyridine) coordination polymer.     

高分子混合物薄膜的相分离行为

从高分子混合物薄膜的相分离行为的机理，相分离后期粗化动力微区尺寸与时间的标度关系，影响高分子混合物薄膜表面形态形成的因素等几个方面对近年来高分子混合物薄膜相行为的研究进展进行总结，概述了今后可能的发展趋势。     

Chromatographic Behaviour of Amino Sugars on Metal Salt Impregnated Thin Layers

Abstract

Suitable TLC separation scheme for Amino Sugars on silica gel G plates impregnated with metal salt, using the solvent system methanol-acetone (50:10) has been worked out. The visualization of the spots was done by spraying with ninhydrin in 1 - butanol.     

A novel approach to thermal Analysis of Thin films

A novel instrument is described called the Thin film Analyser (TFA) which quantitatively measures changes in mechanical and rheological properties of drying films in-situ on a test panel. It is based around a simple force-sensing device, capable of carrying various probes, which can be positioned in anX-Y plane over the panel. Temperature control is achieved by means of a heating block under the sample. By imposing a thermal gradient along the block, measurements can be obtained at a series of temperatures in a single experiment. Several applications of the TFA to the drying of curable and latex-based coatings are discussed, as well as some more specialized uses. The TFA concept represents a novel approach to the thermal analysis of thin films.The authors gratefully acknowledge the design, engineering and software development work of the Instrument Group at ICI Paints, in particular John Hayton, Neil Burrows, Tony Evans and Ian Francis, who have now built three versions of the TFA.     

X-ray and Raman study of spray pyrolysed vanadium oxide thin films

Vanadium oxide thin films were prepared by spray pyrolysis using solutions of vanadium chloride (VCl₃) with different concentrations on glass substrates heated at 200 and 250 °C. The influence of substrate temperature (T_s) and solution concentration (molarity) on structural and vibrational properties is discussed by using X-ray diffraction and Raman spectroscopy. The results revealed that at 0.05 M and T_s = 200 °C, V₄O₉ thin films are obtained. At 250 °C, V₂O₅ phases with preferential orientation are observed and the films become polycrystalline when the molarity increases.     

Chemistry and Crystal Growth

Single-crystal materials, along with other forms of condensed matter (ceramics, polymers, liquid crystals, etc.) are fundamental to modern technology. The basic research and production of new materials with “tailored” solid-state physical properties therefore necessitate not only chemical synthesis but also the production of single crystals of a particular morphology (either bulk or thin layer crystals) and well-defined crystal defects (doping). In this review, an attempt is made to broaden the traditional synthetic concept of chemistry to the process of single-crystal synthesis. The methods of the resulting approach, which takes into account the specific properties of solid materials, are discussed and illustrated by experimental set-ups for the solution of a range of problems in chemical crystallization. Also included is recent work on the growing of single crystals of high-temperature superconductors, organic non-linear optical compounds, and proteins.     

Simultaneous growth of diamond and nanostructured graphite thin films by hot-filament chemical vapor deposition

Diamond and graphite films on silicon wafer were simultaneously synthesized at 850 °C without any additional catalyst. The synthesis was achieved in hot-filament chemical vapor deposition reactor by changing distance among filaments in traditional gas mixture. The inter-wire distance for diamond and graphite deposition was kept 5 and 15 mm, whereas kept constant from the substrate. The Raman spectroscopic analyses show that film deposited at 5 mm is good quality diamond and at 15 mm is nanostructured graphite and respective growths confirm by scanning auger electron microscopy. The scanning electron microscope results exhibit that black soot graphite is composed of needle-like nanostructures, whereas diamond with pyramidal featured structure. Transformation of diamond into graphite mainly attributes lacking in atomic hydrogen. The present study develops new trend in the field of carbon based coatings, where single substrate incorporate dual application can be utilized.     

Photosensitivity of CuBiSe2 Thin Film Deposited by Vacuum Evaporation Technique

CuBiSe₂ (CBSe) thin film was prepared by vacuum evaporation. The deposited film was characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X‐ray (EDX), UV–visible specroscopy, and I–V analysis. XRD analysis indicates the formation of cubic CBSe thin film, and the corresponding EDX spectrum confirms the stoichiometry composition of CBSe. In the AFM images, the majority of the particles are granular, and the surface roughness is 8.86 nm. The optical absorption coefficient is >10⁴ in the visible region and the bandgap energy is calculated to be 1.84 eV. The photosensitivity of the film is 181%.     

Studies on the Thin Film of TiO2, Fe2O3 and SnO2 by the Organometallic-CVD Technique

Pure TiO_2,Fe_2O_3 and SnO_2 are wide-bandgap semiconductors.Their films have high transparency in visible spectral region.These oxide films have been applied to electronics,optoelectronics, solar cells and display devices.A variety of techniques including reactive sputtering,reactive evaporation, ion-beam evaporation and chemical vapor deposition, and hydrolyses of the respective halides or alkoxides have been employed for the growth of thin films of TiO_2,Fe_2O_3 and SnO_2.In     

氧化锌薄膜的电化学沉积和表征

以透明导电玻璃(TCO)为衬底，用硝酸锌水溶液作为电解液，研究了阴极还原沉积ZnO薄膜的反应机理和电化学行为. 通过改变工艺条件来控制ZnO的生长速率， 得到了粒径为10～15 nm的纳米ZnO薄膜. XRD分析显示纳米ZnO薄膜纯度高， 呈纤锌矿结构. 光学测试结果表明，在可见光区其透光度高达90%，禁带宽度为3.37 eV.     

Electrochemical Characterization of Chemically Synthesized Polythiophene Thin Films: Performance of Asymmetric Supercapacitor Device

Polythiophene (PT) thin films have been prepared by chemical bath deposition (CBD) method at room temperature (300 K) via oxidative polymerization of thiophene using ammonium peroxodisulfate (APS) as an oxidizing agent. Globular particulates of PT are deposited on the stainless steel and glass substrates. The morphology and chain structure of PT are studied using scanning electron microscopy (SEM) and Raman spectroscopy techniques, respectively. The electrochemical behavior of PT electrode is studied using cyclic voltammetry and galvanostatic charge? discharge studies. PT thin film shows maximum specific capacitance of 300 F g^?1 at 5 mV s^?1 in 0.1 M LiClO₄/PC electrolyte. The asymmetric device formed with PT and graphite shows supercapacitive properties useful in the power applications.     

A crystallographic description of experimentally identified formation reactions of Cu(In,Ga)Se2

This work describes solid-state reactions for the formation of the chalcopyrite compounds CuInSe₂, CuGaSe₂ and Cu(In,Ga)Se₂ on atomic scale. The most important chalcopyrite formation reactions which were identified by the authors by real-time in situ X-ray diffraction in preceding experiments are (A) CuSe+InSe→CuInSe₂, (B) Cu₂Se+2 InSe+Se→2 CuInSe₂ and (C) Cu₂Se+In₂Se₃→2 CuInSe₂. During the selenistaion of a metallic precursor containing gallium a separate fourth reaction occurs: (D) Cu₂Se+Ga₂Se₃→2 CuGaSe₂. The quaternary compound is finally formed by interdiffusion of CuInSe₂ with CuGaSe₂ (E). These five reactions differ in their activation energy and reaction speed. We explain these differences qualitatively by analysing the involved crystal structures for each reaction. It turns out that all reactions involved in the formation of Cu(In,Ga)Se₂ are promoted by epitaxial relations, which facilitates the formation of polycrystalline thin films at temperatures much below those necessary for single crystal growth. Recommendations for the growth of larger grains of Cu(In,Ga)Se₂ containing fewer defects are given.