Spectroscopic and electrochemical properties of thin solid films of yttrium bisphthalocyanine

Langmuir—Blodgett (LB) and evaporated thin solid films of the yytrium bisphthalocyanine complex (YPc₂) have been prepared on various substrates. Cyclic voltammograms of films are discussed and the electrochromic effect on LB films is reported. A detailed spectroscopic characterization of the YPc₂ material is given using resonance Raman scattering (RRS), surface-enhanced resonance Raman scattering (SERRS), transmission and reflection absorption FT-IR spectroscopy and UV—vis spectra. The spectroscopic characterization of the chemical and electrochemical oxidations products of YPc₂ films and solutions was carried out by in situ UV—vis spectroscopy. Potential applications are discussed.     

Structural and optical properties of Na doped ZnO nanocrystalline thin films synthesized using sol–gel spin coating technique

Sodium (Na) doped Zinc oxide (ZnO) thin films have been deposited on a glass substrate by the sol–gel spin coating method. Effect of doping with various percentages of Na at a particular annealing temperature of 500 °C is studied. The samples were characterized by X-ray diffraction (XRD), micro-photoluminescence, Raman and Polarized Raman spectroscopy. The X-ray diffraction and micro-Raman spectroscopy confirmed the presence of Na substitution in zinc oxide and the wurtzite structure of the lattice is retained. An enhancement of resonant Raman scattering processes as well as longitudinal optical phonon overtones up to the fifth order were observed in the micro Raman spectra. The similar values of depolarization ratios obtained from Polarized Raman studies recommend no change in the symmetry. Photoluminescence showed a strong emission peak in the near UV at 3.2 eV and negligible visible emission.     

Nanocrystalline Zn1−x−yBexMgyO thin films synthesized by the sol–gel method: structural and near infrared photoluminescence properties

In this paper, we reports on the structural and optical properties of Zn_1?x?yBe_xMg_yO thin films prepared by sol–gel method, which are new materials for optoelectronic and ultraviolet-light-emitting devices. The crystal structure and core level spectra of these films are studied by X-ray diffraction and X-ray photoelectron spectroscopy. Surface morphology of the films is analyzed by scanning electron microscope images and the surface is composed of spherical shaped grains. Micro-photoluminescence shows a near edge band emission and the peak values tuned from 3.26 eV for the undoped to 3.4 eV for the doped ZnO film. Near infrared emission is observed in the region 1.64–1.67 eV for pure and co-doped ZnO films. In micro-Raman spectra, multiple-order Raman bands originating from ZnO-like longitudinal optical (LO) phonons are observed. A Raman shift of about 5–18 cm^?1 is observed for the first-order LO phonon. A comparative study was made on Raman band for BeZnO, MgZnO and BeMgZnO nanocrystals with the LO phonon band of bulk ZnO. The ultraviolet resonant Raman excitation at room temperature shows multi-phonon LO modes up to the fourth order. Deformation energy of all the films is calculated and BeMgZnO film has the minimum deformation energy.     

显微共焦拉曼光谱研究电化学合成聚苯胺膜

显微共焦拉曼技术被用来研究电化学合成的聚苯胺（PANI）膜. 研究结果表明：在不同的激发光聚焦深度，聚苯胺膜的拉曼光谱有明显变化.从而反映出聚苯胺膜的掺杂程度在膜生长过程中随膜厚度的增长而增加. 并由X射线电子能谱（XPS）和紫外吸收光谱（UV）分析证实.     

Electrodeposition of thin Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> films

The electrochemical behavior of copper(II), zinc(II), and thiosulfate (S₂O₃ ^2-) ions on the molybdenum electrode in individual 0.2 М sodium sulfate solutions (рН 6.7) and with addition of either 0.1 М tartaric acid (рН 4.6) or 0.1 М citric acid (рН 4.7) is studied. A one-step electrochemical method is developed for the deposition of thin Cu₂ZnSnS₄ films, which is carried out on the molybdenum electrode at a constant potential in sodium sulfate solutions containing tartaric acid. The effect of the concentration of electrolyte components on the chemical composition of Cu₂ZnSnS₄ films is determined. The phase composition is confirmed by the Raman spectroscopy data. The surface morphology of synthesized films is studied by means of scanning-electron and atomic-force microscopes. The photoelectrochemical characteristics of Cu₂ZnSnS₄ films are determined. Samples of these coatings on the Mo electrode are found to be highly photosensitive.     

Chloroaluminum phthalocyanine thin films: chemical reaction and molecular orientation

The chemical transformation of the polar chloroaluminum phthalocyanine, AlClPc, to μ-(oxo)bis(phthalocyaninato)aluminum(III), (PcAl)₂O, in thin films on indium tin oxide is studied and its influence on the molecular orientation is discussed. The studies were conducted using complementary spectroscopic techniques: Raman spectroscopy, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. In addition, density functional theory calculations were performed in order to identify specific vibrations and to monitor the product formation. The thin films of AlClPc were annealed in controlled environmental conditions to obtain (PcAl)₂O. It is shown that the chemical transformation in the thin films can proceed only in the presence of water. The influence of the reaction and the annealing on the molecular orientation was studied with Raman spectroscopy and NEXAFS spectroscopy in total electron yield and partial electron yield modes. The comparison of the results obtained from these techniques allows the determination of the molecular orientation of the film as a function of the probing depth.

Surface-enhanced Raman scattering and micro-Raman imaging of Langmuir-Blodgett films of rhodium phthalocyanine

Rhodium phthalocyanine (RhPc) was synthesized and ultra thin Langmuir-Blodgett (LB) films of RhPc were successfully fabricated. The LB film characterization was carried out using both UV-vis absorption spectra and Raman scattering. The Raman spectroscopy was carried out using 633 and 780 nm laser lines. LB films were deposited onto Ag nanoparticles to achieve the surface-enhanced pre-resonance Raman scattering (pre-SERRS) and surface-enhanced Raman scattering (SERS) for both laser lines, respectively, which allowed the characterization of the RhPc ultra thin films. The morphology of the LB RhPc neat film is extracted from micro-Raman imaging.     

Study of poly[bis(p-toluene sulfonate) diacetylene] films prepared by a modification of the Langmuir–Blodgett technique

Coherent this films of poly[bis(p-toluene sulfonate) diacetylene] were successfully formed by modified Langmuir–Blodgett techniques using two methods: (i) Photopolymerization of the monomer film at the gas/liquid interface and then transfer to a solid substrate, and (ii) transfer of the monomer film to the solid substrate and subsequent photopolymerization on the substrate itself. The films thus obtained were characterized by traditional force–area isotherms while on pure water subphases. Segments were transferred at either 1 or 10 dyn/cm surface pressure, in different stages of photopolymerization, to glass or germanium substrates. The films on the substrate were characterized by the methods of multiple attenuated-internal-reflection infrared spectroscopy, ellipsometry, contact-potential measurement, and laser Raman spectroscopy. Our results show that the films are multimolecular and about 100 Å thick. Of special interest were the observation of significant anisotropy of oriented dipoles and the ability to obtain excellent spectral data for these very thin oriented films. Raman spectroscopic features are similar to those observed for the bulk polymer, even in the low-frequency region. Polarized Raman spectroscopy confirmed the presence of local anisotropy in these films.     

Monitoring of the Sol-Gel Synthesis of Organic-inorganic Hybrids by FTIR Transmission,FTIR/ATR,NIR and Raman Spectroscopy

Summary: The sol-gel synthesis of organic-inorganic hybrids based on triethoxysilane- terminated poly(ethylene oxide) and tetraethylorthosilicate was monitored in-situ using three spectroscopic methods (FTIR/ATR, Raman, NIR). These spectroscopic methods allow in-situ monitoring of the evolution of hybrid materials starting from the modification of the polymer and the early steps of hydrolysis up to the network formation. By application of ²⁹Si solid-state NMR spectroscopy the assignment and quantification of the Raman bands to different end groups and different cross-linking states was made. The sol-gel reaction was also followed by in-line NIR spectroscopy. A multivariate data analysis was accomplished to obtain a conversion-time curve. Furthermore, we investigated spin-coated films on wafers using FTIR transmission spectroscopy.     

The effect of Sn dopant on crystal structure and photocatalytic behavior of nanostructured titania thin films

In this study, preparation of Sn doped (0–30 mol % Sn) TiO₂ dip-coated thin films on glazed porcelain substrates via sol–gel process have been investigated. The effects of Sn content on the structural, optical, and photo-catalytic properties of applied thin films have been studied by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), field emission SEM (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). Surface topography and surface chemical state of thin films were examined by atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). XRD patterns showed an increase in peak intensities of the rutile crystalline phase by increasing the Sn dopant. The prepared Sn-doped TiO₂ photo-catalyst films showed optical absorption edge in the visible light area and exhibited excellent photo-catalytic ability for degradation of methylene blue solution under UV irradiation. The result shows that doping an appropriate amount of Sn can effectively improve the photo-catalytic activity of TiO₂ thin films, and the optimum dopant amount is found to be 15 mol%. The Sn⁴⁺ dopants substituted Ti⁴⁺ in the lattice of TiO₂ and increased surface oxygen vacancies and the surface hydroxyl groups. TEM results showed small increase in planar spacing (was detected by HR-TEM caused by Sn dopants in titania based crystals).     

Micro-Raman and Tip-Enhanced Raman Spectroscopy of Carbon Allotropes

Summary: Raman spectroscopic data are obtained on various carbon allotropes like diamond, amorphous carbon, graphite, graphene and single wall carbon nanotubes by micro-Raman spectroscopy, tip-enhanced Raman spectroscopy and tip-enhanced Raman spectroscopy imaging, and the potentials of these techniques for advanced analysis of carbon structures are discussed. Depending on the local organisation of carbon the characteristic Raman bands can be found at different wavenumber positions, and e.g. quality or dimensions of structures of the samples quantitatively can be calculated. In particular tip-enhanced Raman spectroscopy allows the investigation of individual single wall carbon nanotubes and graphene sheets and imaging of e.g. local defects with nanometer lateral resolution. Raman spectra of all carbon allotropes are presented and discussed.     

ZnO thin films prepared on titanium substrate by PLD technique at different substrate temperatures

ZnO thin films were grown by pulsed laser deposition on titanium substrates at different substrate temperatures ranging from 300 to 700 °C. X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS),photoluminescence, and Raman spectroscopy are employed to investigate the change of properties. XRD, XPS, and Raman data showed that the films consisted of TiO₂ at high substrate temperature, which will deteriorate the crystallization quality of ZnO films. The optimum temperature for the growth of ZnO films on the Ti substrate is about 500 °C in this paper. The ZnO films grown on titanium substrate can be used in direct current, microwave, and medical applications. Copyright © 2014 John Wiley & Sons, Ltd.     

Surface analysis of films and film systems produced by pulsed laser deposition

Ceramic films and film systems (ZrO₂ films, ZrO₂/Ti multilayers, and BN films) are deposited by pulsed laser deposition (PLD) and analyzed using X-ray photoelectron (XPS), Auger electron (AES), and micro-Raman spectroscopies. The electron spectroscopies are used to determine the film stoichiometry, the nature of the bonding, and to specify contaminant species. The micro-Raman spectroscopy gives information on crystal structure, grain size, and mechanical stress within the films. In ZrO₂ films a stoichiometry is achieved with typically 5%, with only weak dependencies on processing variables. The only contaminants are a small amount of water from the ambient gas and a carbonaceous surface layer. Multilayers consisting of alternating ZrO₂ and Ti layers exhibit a TiC contamination within the Ti layers. Depending on the processing variables, BN films may be nearly stoichiometric or may have significant, even dominant contaminations throughout the film from elemental B, B₂O₃, and/or a boron-oxynitride species. The first component is due to the non-stoichiometric material removal from the target (N-depletion) at low laser fluences, as confirmed by XPS measurements on irradiated targets. The second and third arise from H₂O in the ambient, and exhibit a complex dependence on processing variables. Micro-Raman spectra show only amorphous or hexagonalphase BN. Depending on the position on the substrate relative to the laser-induced vapour/plasma plume, there may be a particle deposition or mechanical stress within the films, as evidenced from large shifts (up to 15 cm^–1) of the Raman spectral peaks.     

Monitoring electrode/electrolyte interfaces of Li-ion batteries under working conditions: A surface-enhanced Raman spectroscopic study on LiCoO2 composite cathodes

Lithium-ion batteries are commonly used for electrical energy storage in portable devices and are promising systems for large-scale energy storage. However, their application is still limited due to electrode degradation and stability issues. To enhance the fundamental understanding of electrode degradation, we report on the Raman spectroscopic characterization of LiCoO₂ cathode materials of working Li-ion batteries. To facilitate the spectroscopic analysis of the solid electrolyte interface (SEI), we apply in situ surface-enhanced Raman spectroscopy under battery working conditions by using Au nanoparticles coated with a thin SiO₂ layer (Au@SiO₂). We observe a surface-enhanced Raman signal of Li₂CO₃ at 1090 cm⁻¹ during electrochemical cycling as an intermediate. Its formation/decomposition highlights the role of Li₂CO₃ as a component of the SEI on LiCoO₂ composite cathodes. Our results demonstrate the potential of Raman spectroscopy to monitor electrode/electrolyte interfaces of lithium-ion batteries under working conditions thus allowing relations between electrochemical performance and structural changes to be established.     

Synthesis and Characterization of Nanostructured a-C:H (Hydrogenated Amorphous Carbon) Thin Films by Gaseous Thermionic Vacuum Arc (G-TVA) Deposition Technique

The aim of this contribution is to present the properties of the nanostructured hydrogenated carbon thin films and to study their growth carried out in a special deposition technique based on Thermionic Vacuum Arc method. The Gaseous Thermionic Vacuum Arc (G-TVA) technology is an original deposition method performed in a special configuration, consisting of a heated thermionic cathode which provides an electron beam on the anode. The surface free energy was evaluated by contact angle and their optical properties were studied by Filmetrics F20 spectrometry system. Structure of the film has been investigated by Raman spectroscopy as well as the mechanical properties like hardness, wear resistance, film-substrate adhesion. The films showed two distinct Raman characteristic peaks located at 1,350 cm⁻¹ (D-line) and 1,550 cm⁻¹ (G-line), broad for Si and very sharp for glass substrates. The G-TVA enables to prepare soft (hardness ~6 GPa) or hard (~24 GPa) films.     

Fe掺杂对纳米TiO2薄膜的结构与光催化性能的影响

采用溶胶-凝胶法制备了Fe掺杂的TiO2薄膜,利用X射线光电子能谱、X射线衍射技术、显微共聚焦拉曼光谱、紫外可见光谱和原子力显微镜等对薄膜进行表征,以甲基橙为反应模型对光催化活性进行测试。 结果表明,在300~600 ℃焙烧时,TiO2以锐钛矿结构存在,700 ℃焙烧时出现金红石结构。 随掺铁量和焙烧温度的增加,Fe/TiO2薄膜的表面粗糙度和晶粒尺寸均逐渐增大;随镀膜层数的增加,Fe/TiO2薄膜光谱吸收向可见光方向移动;较低含量的铁掺杂改善了TiO2薄膜的光催化活性,而较高含量的铁掺杂则使TiO2薄膜的光催化活性下降,掺铁量为0.1%时Fe/TiO2薄膜的光催化活性最好。     

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.     

Effect of potassium permanganate on morphological,structural and electro-optical properties of graphene oxide thin films

This work investigated the effect of Potassium Permanganate (KMnO₄) on graphene oxide (GO) properties, especially on electrical properties. The GO thin films were deposited on a glass substrate using drop casting technique and were analysed by using various type of spectroscopy (e.g. Scanning Electron Microscopy (SEM), Ultra- Violet Visible (UV–VIS), Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), optical band gap, Raman Spectroscopy). Furthermore, the electrical experiments were carried out by using current–voltage (I-V) characteristic. The GO thin film with 4.5 g of KMnO₄ resulted in higher conductivity which is 3.11 × 10^?4 S/cm while GO with 2.5 g and 3.5 g of KMnO₄ achieve 2.47 × 10^?9 S/cm and 1.07 × 10^?7 S/cm, respectively. This further affects the morphological (SEM), optical (band gap, UV–Vis, FTIR, and Raman), and crystalline structural (XRD) properties of the GO thin films. The morphological, elemental, optical, and structural data confirmed that the properties of GO is affected by different amount of KMnO₄ oxidizing agent, which revealed that GO can potentially be implemented for electrical and electronic devices.     

Structural,compositional and hardness properties of hydrogenated amorphous carbon nitride thin films synthesized by dense plasma focus device

The hydrogenated amorphous carbon nitride (a‐CN_x:H) thin films were synthesized on the SS‐304 substrates using a dense plasma focus device. The a‐CN_x:H thin films were synthesized using CH₄/N₂ admixture gas and 20 focus deposition shots on substrates placed at different distances from the anode top. X‐ray photoelectron spectroscopy and Raman analysis confirmed different C–N bonding in the a‐CN_x:H thin films. A decrease in the N/C ratio as well as the sp³/sp² ratio with an increase in the substrate distance has been observed. The higher amount of C–N formation for the film synthesized at 10 cm is observed which decreases with increasing distance. The X‐ray photoelectron spectroscopy and Raman analysis affirmed the C ≡ N presence in all the thin films synthesized at different distances. The morphology of the synthesized a‐CN_x:H thin films showed nanoparticles and nanoparticle clusters formation at the surface. The hardness results showed comparatively lower hardness of the a‐CN_x:H thin films due to the presence of C ≡ N. The C–N formation with lower amount of C ≡ N and a higher N/C ratio as well as a higher sp³/sp² ratio for the films synthesized at 10 cm show reasonably higher hardness. Copyright © 2016 John Wiley & Sons, Ltd.     

Triton-X mediated interconnected nanowalls network of cadmium sulfide thin films via chemical bath deposition and their photoelectrochemical performance

Thin films of cadmium sulfide (CdS) have been wet chemically deposited onto fluorine-doped tin oxide (FTO) coated conducting glass substrates by using non-ionic surfactant; Triton-X 100. An aqueous solution contains cadmium sulphate as a cadmium and thiourea as sulphur precursor. Ammonia used as a complexing agent. The results of measurements of the x-ray diffraction, Raman spectroscopy, optical spectroscopy, energy dispersive spectroscopy, scanning electron microscopy, Brunauer Emmett Teller (BET) surface areas and atomic force microscopy were used for the characterization of the films. These results revealed that the films are polycrystalline, consisting of CdS cubic phase. The films show a direct band gap with energy 2.39 eV. The films show interconnected nanowalls like morphology with well-defined surface area. Finally, the photoelectrochemical (PEC) performance of Triton-X mediated CdS thin film samples were studied. The sample shows photoelectrochemical (PEC) performance with maximum short circuit current density (J_sc) 1.71 mA/cm² for larger area (1 cm²) solar cells.