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In this work, electrochromic devices were prepared using the redox couple ethyl viologen diperchlorate and 1,1′-diethyl ferrocene in propylene carbonate as an aprotic solvent to facilitate ions separation and diffusion inside the devices. Electrochromic devices were made using electrochromic gel mixtures at the concentrations of 55%, 60% and 65% with respect to the bisphenol A polymer. In particular, two sets of gels were made: one set contained the bisphenol A not-polymerized while and the second one contained the polymerized polymer. Different techniques, such as cyclic voltammetry, UV-vis-NIR, and Raman spectroscopy, were used to study such systems to understand the differences in terms of performances between the different sets of electrochromic devices. Cyclic voltammetry confirmed that the oxidation process of the 1,1′-diethyl ferrocene and the reduction of the ethyl viologen diperchlorate occurred at about 0.4 V. Interesting variations in the transmittances were found between the two groups of samples. The best values of CE were provided by the electrochromic devices based on the polymerized electrochromic gel mixture at a concentration of 60% (EM60). The EM60 device result was CE = 92.82 C/cm2 in the visible region and CE = 80.38 C/cm2 in the near–infrared region, confirming that these devices can be used for energy-saving applications. A structural characterization of the materials used in the two sets of electrochromic devices was made using Raman spectroscopy, and the analysis supports the electrochemical models used to explain the processes involved during operation of the electrochromic systems. [ABSTRACT FROM AUTHOR]

Raman spectroscopy plays a pivotal role in spectroscopic investigations. The small Raman scattering cross-section of numerous analytes, however, requires enhancement of the signal through specific structuring of the electromagnetic and morphological properties of the underlying surface. This enhancement technique is known as surface-enhanced Raman spectroscopy (SERS). Despite the existence of various proposed alternatives, the approach involving Fabry–Pérot cavities, which constitutes a straightforward method to enhance the electromagnetic field around the analyte, has not been extensively utilized. This is because, for the analyte to experience the maximum electric field, it needs to be embedded within the cavity. Consequently, the top mirror of the cavity will eventually shield it from the external laser source. Recently, an open-cavity configuration has been demonstrated to exhibit properties similar to the classic Fabry–Pérot configuration, with the added advantage of maintaining direct accessibility for the laser source. This paper showcases how such a simple yet innovative configuration can be effectively utilized to achieve remarkable Raman enhancement. The simple structure, coupled with its inexpensive nature and versatility in material selection and scalability, makes it an ideal choice for various analytes and integration into diverse Raman apparatus setups. [ABSTRACT FROM AUTHOR]

Graphene oxide and reduced graphene oxide thin films are very promising materials because they can be used in optoelectronic devices and in a growing range of applications such as touch screens and flexible displays. In this work, graphene oxide (GO) and thermally reduced graphene oxide (rGO) thin films, deposited on Ti/glass substrates, have been obtained by electrophoretic deposition. The morphological and the structural properties of the samples have been investigated by micro-Raman technique, X-ray reflectometry, and SEM analysis. In order to study the optical and electrical properties, variable angle spectroscopic ellipsometry and impedance analysis have been performed. The thermal annealing changes strongly the structural, electrical, and optical properties, because during the thermal processes some amount of sp³ bonds originally present in GO were removed. In particular, the annealing enhances the Ohmic behavior of the rGO film increasing its conductivity and the estimated optical density. Moreover, using electrophoretic deposition, we have found a higher value of optical density for GO thin films, not observed in GO films obtained with other deposition methods. [ABSTRACT FROM AUTHOR]

Lead zirconium titanate PbZr0.53Ti0.47O3 (PZT) thin films have been obtained by sol-gel synthesis, deposited on different substrates [float glass, indium tin oxide (ITO)-coated float glass, and intrinsic silicon wafer], and later subjected to different thermal treatments. The morphologic and the structural properties of both PZT thin films and substrates have been investigated by scanning electron microscope and their composition was determined by energy dispersive x-ray (EDX) analysis. Moreover, variable angle spectroscopic ellipsometry provides relevant information on the electronic and optical properties of the samples. In particular, the optical constant dispersion of PZT deposited on ITO-coated float glasses shows a small absorption resonance in the near IR region, not observed in PZT films deposited on the other substrates, so that such absorption resonance can be explained by interfacial effects between ITO and PZT layers. This hypothesis is also supported by EDX measurements, showing an interdiffusion of lead and indium ions, across the PZT-ITO interface, that can generate a peculiar charge distribution in this region. [ABSTRACT FROM AUTHOR]

The solvation mechanism of lithium ions in pure ethylene carbonate (EC) solutions has been studied in a wide concentration range by different techniques and for temperatures up to 100 °C. For low concentrations (R = [Li[sup +] ]/[EC] ≤ 0.1) the solvation number of Li[sup +] cations in the solution has been found to be ∼7, by using nuclear magnetic resonance techniques. This number decreases at higher concentration, and complexes Li[sup +]-EC with ∼3 solvent molecules per cation are formed when R =0.33. The temperature dependence of the solvation has been investigated for the more concentrated solutions by Raman spectroscopy. When the temperature increases, the relative intensity of the Raman bands upshifted by the lithium interaction also increases remarkably, indicating that Li[sup +] ions form complexes with a higher solvation number. On the other hand, a higher degree of reassociation of Li[sup +] cations with perchlorate anions is observed. [ABSTRACT FROM AUTHOR]

Thermoreversible polymer gel electrolytes with ionic conductivities of about 10[SUP-3] S cm[SUP-1] at room temperature, were prepared from poly(acrylonitrile) (PAN)-ethylene carbonate (EC)-LiClO[SUB4] at different solvent/salt ratios. A temperature dependence was investigated for the electrical and mechanical properties, as well as for spectroscopic changes associate to the solvation mechanism of lithium ions in these gel. The measurements performed on this system concern ionic conductivity, study of self-diffusion coefficient by [SUP1]H-NMR, Raman spectroscopy and, finally, an accurate analysis of its mechanical proprieties by rheological tests. The gels present a strong-weak gel transition at about 70 °C, independent from salt concentration hence assignable only to the polymeric matrix. However, this transition is completely reversible on cooling, being this a necessary mechanical property for industrial applications. The Raman study has pointed out an increase, on heating, of the Li[SUP+] coordination number by EC molecules, as well as a growing number of lithium ions involved in the ionic association (Li[SUP+]-solvent-ClO[SUB4]) and in the Li[SUP+]-CN interaction. The experimental evidences suggest an evolution of the system toward a less organized, weak gel configuration, when temperature rises above 65 °C. [ABSTRACT FROM AUTHOR]

The synthesis, morphologic and the structural properties of lead zirconium titanate Pb[Zr.sub.0.53][Ti.sub.0.47][O.sub.3] (PZT) thin films deposited on different substrates such as float glass, indium tin oxide (ITO)-coated float glass, and intrinsic silicon wafer are described. A small absorption resonance in the near infrared (IR) region observed for the optical constant dispersion of PZT deposited on ITO-coated float glasses is explained by interfacial effects between ITO and PZT layers.

Ultraviolet absorption and micro-Raman analyses are used for studying the polymorphism in the growth of titanyl phthalocyanine films on dielectric substrates. Hyperthermal beams have given unprecedented control on the growth, which has produced crystalline films with a controlled structure and different phases even at room temperature and on amorphous substrates, depending on the deposition rate.