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In this article, we succeeded in identifying the absorption peaks that appear in the optical absorption spectra of chromium oxide thin films prepared by the pulsed laser deposition method. It was found that these peaks belong to the nanostructures in the film (chromium particles and chromium oxide nanoparticles). The study included investigating the effect of each of the substrate temperature and laser fluence on the prepared films. We found that heating the substrate to 327 °C leads to a decrease in the concentration chromium nanoparticles. In addition, we found that increasing the laser fluence to 36.7 J cm−2 leads to a significant increase of both the oxygen content and the chromium nanoparticle concentration in the film. [ABSTRACT FROM AUTHOR]

The recent work investigates the relationship between the characteristics of the Raman spectra and the oxidation temperature of thermal-treated graphite samples in air at various temperatures ranging from 200°Cto 800 °C. Our findings indicate that thermal oxidation of graphite in air leads to the enhancement of the 2D vibration pattern while reducing the intensity of the D vibration pattern. Moreover, we report that chemical reduction begins at 550 °C. Furthermore, our results demonstrate that thermal oxidation causes a decrease in the disorder within the samples. [ABSTRACT FROM AUTHOR]

In this paper, we explore the band gap properties of Ag/Ag2O composites synthesized by oxygen plasma treatment of silver thin films as well as the band gap properties of silver nanostructures formed within these composites. The band gap of silver nanoparticles was calculated based on a previous unique result including that the luminescence spectra of the prepared Ag/Ag2O composites contain only features that characterize the various structures of silver nanoparticles. The results obtained showed the formation of energy bands of silver nanoparticles within the energy band structure of the prepared films. Based on the observed features of the luminescence spectra, distinguished energy gaps were found for both individual silver nanoparticles and larger silver nanoparticles. Moreover, the energy gap of individual silver nanoparticles is not significantly affected by neither the size of the silver oxide particles nor the power of the oxygen plasma. [ABSTRACT FROM AUTHOR]

In this work, we highlight the unique relationship between the Fresnel peak and the plasma edge, which are two distinctive features in the optical reflectance spectra of graphite. The optical reflectance spectra were measured for thermal treated graphite samples in air at various temperatures. The effect of the annealing temperature on both the Fresnel peak and the plasma edge was investigated. The results showed that thermal oxidation significantly affects the position of the plasma edge and the characteristics of the Fresnel peak. On the other hand, we found that the relationship between the plasma edge and the position of the Fresnel peak can be used to track the progression of the graphite oxidation process. [ABSTRACT FROM AUTHOR]

In this work, we present the results of a unique study that aims to detect the structural effects on the plasma edges in optical reflectance spectra of Ag/Ag2O composites synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. The results showed that, each of the optical reflectance spectra contains two plasma edges, the first ( λ I) belongs to the surface plasmons of the individual silver nanoparticles, and the second ( λ L) belongs to the larger silver nanoparticles. In addition, we found that the positions of the plasma edges are linearly related to the positions of the optical absorption peaks, except for high and low oxidation rates cases. [ABSTRACT FROM AUTHOR]

In this work, we study a unique phenomenon, which is the formation of surface plasmons on the surface of woven cotton fabrics dyed with reactive red dye and the effect of dye concentration on the surface plasmonicactivity. The results show that a peak was observed in the optical reflectivity spectra, which is an extension of the plasma edge. We called it the plasma peak. It represents the growth and decay phases of the plasmonic activity. Furthermore, the effect of dye concentration on both the plasma edge and the main characteristics of the plasma peak (position, spectral width, and intensity) is investigated. On the other hand, the dye concentration that results in the highest optical activity of surface plasmons was recorded (c = 2%). [ABSTRACT FROM AUTHOR]

In this work, we investigate the structural parameters that affect water adsorption on amorphous carbon nitride thin films synthesized by pulsed laser deposition. The study includes the case of ablation of graphite targets within molecular nitrogen and within a stream of nitrogen plasma afterglow. The results obtained showed that, the effect of Csp2-Csp2 bonds concentration on the adsorption of water molecules depends strongly on the ratio and distortion of the hexagonal rings. Furthermore, analysis of the spectral data showed that, the relationship between the hydrogen bonding strength of water molecules with the film surface and the concentration of Csp2-Csp2 bonds takes a specific mathematical formula in the case of structures composed mainly of hexagonal rings. [ABSTRACT FROM AUTHOR]

The aim of this paper is to compare the spectral features of the response plasmon peak in both the optical absorption and photoluminescence spectra of the Ag/Ag2O composites synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. Results show that close values of the relative area and spectral width of the plasmon response peaks in the optical absorption/photoluminescence spectra were obtained in the case of samples with high oxygen content. In addition, the intensity ratio (Iabsorption/Iluminescence) of these samples decreases linearly with increasing silver oxide grain size. [ABSTRACT FROM AUTHOR]

In this work, we evaluate the effect of both chromium nanoparticles and chromium oxide nanoparticles on the optical reflectance spectra of Cr/Cr2O3 compositions prepared using pulsed laser deposition method. The concentration of nanoparticles was controlled by varying the preparation conditions (the substrate temperature and laser fluence). The results showed that varying the preparation conditions does not significantly affect the plasma edge position of chromium nanoparticles. On the other hand, a shift in the plasma edge position of chromium oxide nanoparticles was observed when heating the substrate to 327 °C. This shift becomes larger when increasing the laser fluence to 36.7 J.cm-2. Furthermore, the results showed that the surface topography does not significantly affect the mechanism of interaction between light and surface plasmons. [ABSTRACT FROM AUTHOR]

In this paper we show that, in a-CNx thin films, the nonlinear relationship between the charge effect resulted during XPS surface analysis and the C(sp³)-N bonds concentration is a direct result of the C-C bonds polarization. We found that the charge effect coefficient relates to both the number of C(sp³)-N bonds and the number of dipoles resulting from C-C bonds polarization. In addition, the results showed that the C-C bonds polarization is the main reason for the clustering processes. [ABSTRACT FROM AUTHOR]

In this study, the structural and optical properties of aluminum oxide thin films were investigated. Aluminum oxide thin films were prepared on silicon and glass substrate by DC magnetron sputtering of aluminum targets with subsequent thermal oxidation of the aluminum-deposited thin films. Important result obtained included the presence of a plasma edge for the individual aluminum atoms. In addition, the temperatures that resulted in the highest concentration of surface plasmons were determined. On other hand, the relationship between the plasma edge and the optical energy gap was investigated. [ABSTRACT FROM AUTHOR]

In this work, we present a more complete description of the optical properties of the silver nanoparticles formed in silver oxide thin films. Ag/Ag2O composites were synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. The results showed that exposing silver thin films to oxygen plasma afterglow leads to a monocrystalline structure of silver oxide. Consequently, the relationship between the crystal size and the characteristics of the plasmon optical absorption peaks was studied. A slight degradation of plasmon peaks of the individual silver nanoparticles was observed. We suggested that this degradation might be due to the mutual interaction between the individual silver nanoparticles located near the Ag2O grain shell and the larger silver nanoparticles in neighboring grains. We found that the degree of degradation is related to the Ag2O grain size. On the other hand, the origin of each fluorescence peak in the Raman spectra of the prepared films was determined. [ABSTRACT FROM AUTHOR]

In this paper, we employ the results of spectral measurements performed using XPS, Raman scattering and UV-VIS techniques to investigate the relationship between the optical band gap and the structural composition of amorphous carbon nitride thin films. From the point of view of the electronic structure of amorphous carbon nitride thin films with relatively high nitrogen content (N/C ≥ 0.1) the results have shown that the case where the C(sp2)–N and C(sp3)–N bonds concentrations are equal is an approach to the case of amorphous carbon (a-C), and therefore the optical band gap is controlled only by the π electron delocalization in C(sp2)–C bonds. This was demonstrated by investigating the direct proportion between Raman ratio ID/IG and 1/Eg2. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effect of different type of target on spectroscopic features of titanium dioxide thin films prepared by laser ablation method. The results of this structural study show that the sample deposited using metallic titanium (Ti) target contains a large proportion of developed rutile phase. However, the sample deposited using pressured annealed disc of titanium oxide (TiO2) target mainly consists of anatase phase. This study also found that the use of metal targets leads to higher optical transparency and a higher energy band gap. [ABSTRACT FROM AUTHOR]

The structure of amorphous CNX thin films have a variety of chemical bond, and studies on these bonds ratios is very important because these ratios determine the appropriate technical use of these films. Therefore, this paper aim to investigate the relation between the conditions of preparation (deposition pressure) of a-CNx thin films prepared using PLD (Pulsed Laser Deposition) method and the film's structure. Results shown that the deposition pressure variation does not affecting the concentration in the same manner for all bonds in the film. Moreover, the sp2 cluster size and the order degree are related to the numerical value of the deposition pressure. [ABSTRACT FROM AUTHOR]

In this study, silver oxide thin films were deposited on silicon and glass substrates using thermal evaporation techniques without oxygen atmosphere with subsequent annealing in air. The deposited films were annealed in air at 100 and 450 C° respectively. Optical properties show very low transparency at lower oxidation temperature. The transparency increased to an average value of55% when applying annealing temperature of 450 C°. The optical band gap of Ag2O thin films increases from 0.92 eV to 1.73 eV as the annealing temperature increases from 100°C to 450°C. [ABSTRACT FROM AUTHOR]

The aim of this paper is to investigate the relationship between the micro structure and the surface charge effect resulted during XPS surface analysis of amorphous carbon nitride thin films prepared by laser ablation method. The study results show that the charge effect coefficient ( E ) is not just a correction factor. We found that the changes in this coefficient value due to incorporation of nitrogen atoms into the carbon network are related to the spatial configurations of the sp 2 bonded carbon atoms, order degree and sp 2 clusters size. In addition, results show that the curve E vs. C(sp 3 )-N is a characteristic curve of the micro structure. This means that using this curve makes it easy to sorting the samples according to the micro structure (hexagonal rings or chains). [ABSTRACT FROM AUTHOR]

The aim of this paper is to develop the understanding of the mechanism which explains the formation of the (1000–1800) cm − 1 band in FT-IR spectra of amorphous carbon nitride thin films prepared by laser ablation method. The study results show that the bonds C(sp 3 ) N is have significant role in the formation of the (1000–1800) cm − 1 band, and it is necessary to provide a minimum amount of these bonds to be able to contribute in breaking the symmetry of the sp 2 carbon bonds. [ABSTRACT FROM AUTHOR]

This research highlight an innovative method for calculating the optical band gap of thin layers of aluminum oxide resulting from the surface oxidation of non-transparent samples of aluminum. The aluminum samples were prepared using the compressing and annealing methods. Thermal heating in suitable oven was used for annealing procedures. The effects of annealing temperature on structural and optical properties of studied samples were investigated by measuring the optical band gaps and FT-IR spectra. The results show that the annealing temperature affects the structural and optical properties of the surface layer. In addition, it was found that in the case of annealing temperature at 1000°C, the optical band gap of alumina samples was found to be 4.99 and 4.19 eV at annealing times of 2 and 4 hours respectively. On the other hand, at the temperature of 500°C, the surface has metallic properties because the area of the oxide layer is very small. This indicates that the annealing temperature has great role in determining the properties of the surface layer. [ABSTRACT FROM AUTHOR]

4 The position of plasma peak as a function of dye concentration Graph: Fig. A Undyed sample, B-F dyed samples at a concentration of B 1%, C 2%, D 3%, E 4%, and F 5% Graph: Fig. 5 The full widths at half maximum of plasma peak as functions of dye concentration The original article has been corrected. [Extracted from the article]

In this work, we present the results of a unique study that aims to detect the degradation of the individual silver nanoparticles peak in the photoluminescence spectra of the Ag/Ag 2 O composites synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. The analysis of the spectroscopic data yielded an interesting finding that, the individual silver nanoparticles peak degradation observed in the optical absorption spectra has a mirror image in the photoluminescence spectra. In addition, we found that this degradation arises due to the mutual interaction between the individual silver nanoparticles located near the Ag 2 O grain shell and the larger silver nanoparticles inside the grain and it related to the silver oxide grain size. • As in the case of optical spectra absorption spectra, a slight degradation of luminescence peaks of the individual silver nanoparticles (peak I) was observed. We suggested that this degradation might happen due to the dipole – dipole interaction occurring inside the grain. • The polarity is one of the factors contributing to the degradation of the peak I that belong to individual silver nanoparticles. • The degree of degradation (the ratio p 2 /p 1) is related to the Ag 2 O grain size. • Equation (3) is the main result of this research, and it explains why the spectra of absorption and luminescence of the individual silver nanoparticles are not completely similar, despite the achievement of the mirror-image rule. [ABSTRACT FROM AUTHOR]