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Bulk phosphorus oxynitride (PON), isoelectronic with SiO2, is confirmed to have many polymorphs as the latter. However, its 2D counterparts have not been studied. In this work, crystal structure exploration and property study are performed on 2D PON with the help of first‐principle calculation. Three 2D PON sheets are found with thermal, dynamical, and mechanical stability and all of them can be viewed as oxygen‐doped known 2D γ phosphorus nitride (γ‐PN). In the studies, it is indicated that they are indirect bandgap materials with gap values larger than 3 eV. The situations of orbital hybridization are discussed and their bonding properties are analyzed. Infrared vibrational spectra of these 2D materials are simulated and the vibrational modes at the Brillouin center are assigned by the factor group analysis. The reasons for the disappearance of some infrared peaks in the simulated spectra are revealed based on the calculated Born effective charges and vibrational eigenvectors. Their piezoelectric stress tensors are computed via density‐functional perturbation method and the piezoelectric strain tensors are also deduced via the calculated elastic constants. In the results, it is uncovered that these 2D PON sheets have considerably greater piezoelectric coefficients than the primitive 2D γ‐PN, which make them promising for nanopiezoelectric use. [ABSTRACT FROM AUTHOR]

BiOX (X = Cl, Br, I) monolayers are photocatalytic materials having many potential applications, but their basic properties are still not systematically studied. Herein, first‐principles calculations are performed to study their electronic, mechanical, and infrared properties. Band structures calculated by the Heyd–Scuseria–Ernzerhof (HSE06) functional with and without spin orbital coupling uncover that they are indirect bandgap materials. Partial densities of states of these materials are computed and compared to reveal the reason for the differences among their band structures. Studies imply that the BiO bonds are chiefly covalent while the interaction between the Bi and the X atoms is mainly ionic. Elastic constants and ideal in‐plane stresses of these materials are computed to explore their mechanical properties. Performed factor group analyses indicate that there are nine Raman‐active and six infrared‐active modes in their Brillouin zone centers. Their infrared spectra are simulated and the reason for the disappearance of some infrared peaks is given. Comparisons on the above properties are also made for these BiOX monolayers. [ABSTRACT FROM AUTHOR]

The use of Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) characterizations have been indispensable techniques in distinguishing purity of the samples. These techniques give spectra that will be used to analyze the composition, morphology, purity, among others, of the material. One of its interesting applications is to assess elemental and chemical contaminations on second hand clothing. In this study, second hand (Ukay-Ukay) cotton garments from selected flea market sites in Valencia City, Bukidnon, Philippines were examined quantitatively for microbial and chemical contaminations by using FTIR, SEM, and EDX. The FTIR results obtained in both sites showed broad peaks at ~3336 cm-1 attributed to OH functional group, and absorption peaks at 2901.30 cm-1 associated to C-H bond, 1159.70 cm-1, 1107.44 cm-1 and 1053.82 cm-1 attributed to the stretches of CO bond. All of them were characteristics of cotton material. We observed degradation of the cotton material on both sites evident in the decreasing intensity of OH stretching (at peaks around ~3334 cm -1 [site A] and ~3332 cm -1 [site B]) and C-O stretching (around ~1500-1700 cm-1). These were due to the presence of microorganisms such as fungi (e.g. Aspergillus species). The degradation was also observed in the SEM results. Furthermore, peaks related to carboxylate contaminants were observed in both sites around ~1600 – 1800 cm-1 that may be caused by the exposure of the cotton garments in hydrochloric acid (HCl). In general, the characterization results on both sites indicated traces of microorganisms and that the second-hand cotton clothes were contaminated by hazardous chemicals.

Abstract Ge-based alloys have drawn great interest as promising materials for their superior visible to infrared photoelectric performances. In this study, we report the preparation and optical properties of germanium-bismuth (Ge1-xBix) thin films by using molecular beam epitaxy (MBE). GeBi thin films belong to the n-type conductivity semiconductors, which have been rarely reported. With the increasing Bi-doping content from 2 to 22.2%, a series of Ge1-xBix thin film samples were obtained and characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. With the increase of Bi content, the mismatch of lattice constants increases, and the GeBi film shifts from direct energy band-gaps to indirect band-gaps. The moderate increase of Bi content reduces optical reflectance and promotes the transmittance of extinction coefficient in infrared wavelengths. The absorption and transmittance of GeBi films in THz band increase with the increase of Bi contents.

Spinel ferrites having Mg0.6 − xCoxZn0.4Fe2O4 (0 ≤ x ≤ 0.6) compositions were prepared using the sol-gel method. XRD patterns show that samples have the cubic phase of the spinel ferrite with the Fd3̄m space group. The obtained values of the lattice constant and porosity increase with increasing cobalt concentration. FTIR spectra show only the tetrahedral stretching peaks that are shifting towards higher frequencies with increasing Co content. The substitution of Mg by Co leads to the decrease of conductivity of the samples. The behaviors of the real part of permittivity and loss tangent have been investigated using Maxwell theory. Electrical modulus and impedance results show the presence of the electrical relaxation phenomenon for the samples with non-Debye type. The Nyquist representations have been analyzed using a proposed electrical circuit, and the results show that the resistances of the prepared samples resulted mostly from the grain boundary effect. [ABSTRACT FROM AUTHOR]

Ge-based alloys have drawn great interest as promising materials for their superior visible to infrared photoelectric performances. In this study, we report the preparation and optical properties of germanium-bismuth (GeBi) thin films by using molecular beam epitaxy (MBE). GeBi thin films belong to the n-type conductivity semiconductors, which have been rarely reported. With the increasing Bi-doping content from 2 to 22.2%, a series of GeBi thin film samples were obtained and characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. With the increase of Bi content, the mismatch of lattice constants increases, and the GeBi film shifts from direct energy band-gaps to indirect band-gaps. The moderate increase of Bi content reduces optical reflectance and promotes the transmittance of extinction coefficient in infrared wavelengths. The absorption and transmittance of GeBi films in THz band increase with the increase of Bi contents. [ABSTRACT FROM AUTHOR]

Lithium sodium fluoroborate glasses doped with vanadium ions were prepared by melt annealing technique. The structural investigation shows the formation of probable BO 3 , BO 4 , BO 2 F, and BO 3 F structural units. Moreover, vanadium ions are mostly presented in such glasses as V 4 + state and it may form non-bridging oxygens (NBOs). The decreasing in the optical band gap values as a function in the glass composition or vanadium content approves the formation of NBOs. The refractive index is estimated directly from the optical band gap values by using the Dimitrov-Sakka relation. Density, molar volume, molar refraction, and metallization criterion were studied and explained in terms of the structural changes obtained by the impact of the vanadium ions. Thermal activation energy is explained by the formation of Non-bridging oxygens and the effect of V 2 O 5 dopant. [ABSTRACT FROM AUTHOR]

We review the present theoretical and empirical knowledge for α s , the fundamental coupling underlying the interactions of quarks and gluons in Quantum Chromodynamics (QCD). The dependence of α s ( Q 2 ) on momentum transfer Q encodes the underlying dynamics of hadron physics—from color confinement in the infrared domain to asymptotic freedom at short distances. We review constraints on α s ( Q 2 ) at high Q 2 , as predicted by perturbative QCD, and its analytic behavior at small Q 2 , based on models of nonperturbative dynamics. In the introductory part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain. In the second, more technical, part of the review, we discuss the behavior of α s ( Q 2 ) in the high momentum transfer domain of QCD. We review how α s is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as “Commensurate Scale Relations” which connect the various definitions of the QCD coupling without renormalization-scale ambiguity. We also report recent significant measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the “Principle of Maximum Conformality”, which enhances QCD’s predictive power by removing the dependence of the predictions for physical observables on the choice of theoretical conventions such as the renormalization scheme. In the last part of the review, we discuss the challenge of understanding the analytic behavior α s ( Q 2 ) in the low momentum transfer domain. We survey various theoretical models for the nonperturbative strongly coupled regime, such as the light-front holographic approach to QCD. This new framework predicts the form of the quark-confinement potential underlying hadron spectroscopy and dynamics, and it gives a remarkable connection between the perturbative QCD scale Λ and hadron masses. One can also identify a specific scale Q 0 which demarcates the division between perturbative and nonperturbative QCD. We also review other important methods for computing the QCD coupling, including lattice QCD, the Schwinger–Dyson equations and the Gribov–Zwanziger analysis. After describing these approaches and enumerating their conflicting predictions, we discuss the origin of these discrepancies and how to remedy them. Our aim is not only to review the advances in this difficult area, but also to suggest what could be an optimal definition of α s ( Q 2 ) in order to bring better unity to the subject. [ABSTRACT FROM AUTHOR]

• The mechanism of impurity absorption and heterophase inclusion in Ge-As-S glass was investigated. • Heterophase inclusions in Ge-As-S glass can be effectively suppressed by dynamic distillation and melting at the optimized melting temperature. • The average loss of purified fiber and unpurified one is 1.86 dB/m and 2.87 dB/m, respectively. About 1 dB/m decrease in the loss is due to the absence of the visible heterophase inclusion particles in the glass. Strong absorption from the impurities and background scattering induced by heterophase inclusions are major issue in the applications of Ge-As-S glass in mid-infrared (MIR). Here, we report that, the absorption of impurities sourced from raw materials can be removed effectively by oxygen getters and hydrogen getters under static vacuum distillation, leading to almost disappearance of the absorption at 3.11 μm due to S H, <4.08 ppm at 4.01 μm due to S H and < 11.03 ppm at 7.5 μm due to As-O, respectively, in Ge 10 As 28 S 62. The impurities of H 2 O and CO 2 can be further eliminated to near zero by dynamic distillation. On the other hand, the heterophase inclusions, originating from raw materials of sulfur, arsenic and germanium, the silica-container and deoxidizer of Mg, can be eliminated thoroughly by dynamic distillation and optimized melting temperature. We draw the fibers using unpurified and purified glasses and found that, comparing with the fiber loss of 2.87 dB/m at unpurified glass, the optical loss can be decreased to about 1.86 dB/m in purified glass without any visible particles or heterophase inclusions. All the results pave the way of developing low loss Ge-As-S glass fiber for high power laser delivery. [ABSTRACT FROM AUTHOR]

This paper studies the different surfactants and oxidant for the synthesis of polypyrrole (PPy) for the impact, characterizing the Ppy mainly from the surface morphology, conductivity σ, infrared Emissivity and electromagnetic parameter. Using p-Toluenesulfonic Acid(p-TSA),Camphorsulfonic Acid,Sodium(CAMP), p-Toluenesulfonic Acid,solium(P-TSANa), dodecyl benzene sulfonate(DBSA) and cetyl trimethyl ammonium bromide(CTAB) as a surfactant, respectively. Using ferric chloride(FeCl3) and ammonium persulfate(APS) as oxidant, Synthesized by chemical oxidation of polypyrrole nanocomposite materials. By scanning electron microscopy, Fourier transform infrared emission spectroscopy, four-probe, and electromagnetic parameter of the samples were characterized, according to the test results by such instruments, it is found that polypyrrole doped with different surfactants and oxidant can make the infrared emissivity and micro-wave property adjustable. [ABSTRACT FROM AUTHOR]

Abstract: Glasses of the composition 5 ZnO–(50−x) As2O3–45 Sb2O3:x MoO3, with six values of x ranging from 0 to 10mol% are prepared. The samples are characterized by X-ray diffraction, scanning electron microscopy and differential thermal analysis (DTA) techniques. A number of studies, viz., spectroscopic properties (optical absorption, IR, Raman, and ESR spectra), magnetic susceptibility and dielectric properties (dielectric constant ε′, loss tan δ, ac conductivity σac over a wide range of frequency and temperature as well as dielectric break down strength at room temperature), are carried out as a function of molybdenum ion concentration and analyzed in the light of different oxidation states of molybdenum. The analyses of the results indicate that molybdenum ions mostly exist in Mo5+ state rather than in Mo6+ state. [Copyright &y& Elsevier]

Abstract: Glasses of the system xPbO–RNa2B4O7–(100− R − x)CAS with 0⩽ x ⩽50, and 50⩽ R ⩽75mol% have been synthesized in two compositional series and characterized by FTIR, and acoustics to explore the role of PbO on the structure of the glasses. The elastic properties of glasses have been investigated using sound velocity measurements at 4MHz. According to the IR analysis, there is a depolymerization of the silicate network and a conversion of BO3 into BO4 structural units with the formation of non-bridging oxygens. PbO is incorporated into borosilicate network via B–O–Pb, and Si–O–Pb bonds. It is assumed that PbO plays the role of a modifier by replacing the high strength B–O bond with a lower strength Pb–O bond which decreases the glass-transition temperature Tg . The increase of the density was attributed to the replacement of less dense borosilicate structural units by the more dense lead structural units. The observed compositional dependence of the ultrasonic velocity and the elastic moduli was interpreted in terms of the effect of PbO on the coordination of the borate structural units with oxygens and the depolymerization of the silicate network. [Copyright &y& Elsevier]

Abstract: ZnO/niobate composites were first synthesised through the exfoliation of layered niobate and restacking of nanosheets in solution, followed by heat-treatment. The effects of pH and content of solution on the structure and interlayer guests of the self-assembled compounds were systematically investigated. All the as-prepared samples obtained at the conditions of 0.1molL−1 with pH from 11.2 to 12.7, can be indexed to tetragonal symmetry. The amount of interlayer Zn-species tends to decrease slightly as the pH value increases, while it increases markedly with an increase of content and subsequently affects the photoluminescence of the heated-samples. Photoluminescent spectra of all the heated-samples show blue-shifts of 0.15–0.22eV with respects to the bulk ZnO band gap (3.26eV) due to quantum confinement. The UV emission at 359nm obviously weakens and the emission at 398nm gradually enhances as content of increases from 0.1 to 0.8molL−1. [Copyright &y& Elsevier]

Abstract: Mineral powders were added into fumed silica as IR opacifers in order to develop opacified thermal insulating composites for application at high temperatures up to 1000°C. The opacifying effect was evaluated with effective specific extinction. The results indicated that opacifiers could effectively block IR radiation heat transfer and improve thermal insulating properties of fumed silica. Among four opacifiers investigated in this paper, SiC was proved to be the best one for excellent extincting performance. When SiC was adopted with average particle size of 3.029μm and mass ratio of 25%, the values of effective specific extinction increased from less than 12.6 m2/kg to about 55 m2/kg in the wavelength range from 2.5 to 7μm. It was demonstrated that fumed silica-opacifier composites are efficient high temperature insulating materials. [Copyright &y& Elsevier]

Abstract: Undoped and cobalt-doped sodium phosphate glasses of various compositions and with varying cobalt contents were prepared. UV–visible absorption spectra were measured before and after successive gamma irradiation. Experimental results indicated that the undoped base glass reveals strong ultraviolet absorption which is related to the presence of unavoidable trace iron impurities in the raw materials. Cobalt-doped glasses show characteristic visible absorption bands which are related to the presence of Co2+ ions mostly in the tetra-coordination state. The generated induced color centers in the UV and visible regions by gamma irradiation are characterized in relation to intrinsic defects from the host base sodium phosphate glass and the extrinsic defects from both trace iron impurities and added doped cobalt ions. Infrared absorption measurements were carried out for some selected samples to identify the structural building groups in the studied glasses. Cobalt ions showed a shielding behavior towards the effects of progressive gamma irradiation especially in the visible spectral region. [Copyright &y& Elsevier]

Abstract: The impurity content and microhomogeneity of Ge25Sb10S65 glass samples, prepared by direct synthesis from elements, were investigated. It was shown that the increase in temperature of synthesis of the glass-forming melt resulted in the increase of the content of impurities of H, Na, Al, Si, K, Ca and transition metals in the prepared glasses. The glasses from the melt, subjected to chemical-distillation purification, were characterized by the low content of gas-forming impurities and the increased content of Al, Si and Cl. The glasses contained heterophase impurity inclusions mainly consisting of SiO2, and their concentration and size depended on the conditions of glass preparation. The impurity content in the purest glasses was as follows: oxygen – <0.5ppmwt, carbon – <5ppmwt, hydrogen – 0.1ppmwt, Si – <1ppmwt, transition metals – <0.25ppmwt, heterophase impurity inclusions with sizes larger than 80nm – <102 cm3. It was shown that heterophase impurity inclusions behaved as the centers of glass crystallization. [Copyright &y& Elsevier]

Abstract: Preparation of unhydrolyzed and hydrolyzed cotton linters as well as their derivatives (carboxylate, phosphate and phosphosulphonate), vibrational structure and dielectric properties were studied in this work. The vibrational modes were analyzed by FTIR spectroscopy and the band at 1730cm−1 in the carboxylation of unhydrolyzed and hydrolyzed was appeared due to introduce of carboxylic group. The new bands appeared at 1208 and 1400cm−1 in the phosphorylation and phosphosulphonation assigned to C–O–P and C–O–S, respectively. The data indicated that, new chemical structure for the derivatives of unhydrolyzed and hydrolyzed cotton linter was formed. The crystallinity index (CrI) was measured from absorbance ratio of the band 1428 and 900cm−1. The real part of dielectric constant (ε′) and AC electrical conductivity was studied in the temperature range (295–375K) at two different frequencies, 800 and 2000kHz. The ε′ was decreased with increasing frequency due to dispersion. The frequency–temperature dependent conductivity and mechanisms of the electronic conduction were discussed. [Copyright &y& Elsevier]

Abstract: Te80− x Ge20Se x glasses have been prepared along the GeSe4–GeTe4 axis using the classical method in silica tube under vacuum. A phase separation domain appears for composition around Te40Ge20Se40. Our attention was turned toward the Te-rich compositions corresponding to 1< x <5 at.%. These glasses are transparent from 4 to about 20μm without any purification of the starting elements. Furthermore the difference ΔT between the crystallization temperature Tx and the vitreous transition temperature Tg lies at about 110°C that is to say 30°C higher than for the GeTe4 reference glass. Finally the introduction of a few percentages of Se makes the glasses much easier to prepare and more stable against crystallization, making them drawable as optical fibers for example. Taking into account their transparency window, encompassing the CO2 absorption band around 15μm, the Te80− x Ge20Se x with 1< x <5 at.% could become matchless composition for the CO2 infrared detection as planed by the Darwin mission of the European Space Agency. [Copyright &y& Elsevier]

Abstract: The chalcogenide multilayers were prepared as dielectric mirrors having the first order stop bands in the near infrared region ∼1.55μm. The 7.5 layer pairs of the alternating amorphous Sb–Se and As–S layers were deposited on glass substrates using a conventional thermal evaporation method. To center the stop bands of the 15-layer dielectric mirrors at 1.55μm, the layer thicknesses 117nm for Sb–Se and 169nm for As–S single layers were calculated from the quarter wave stack condition. The optical reflection and transmission spectra of the prepared mirrors were measured using a UV/VIS/NIR and FT-IR spectroscopy at the ambient and elevated temperatures. The optical reflection of the annealed 15-layer chalcogenide mirror was found higher than 99% in the range of 1440–1600nm. As the 200nm thick gold layer was added between the substrate and the chalcogenide mirror, the stop band of the annealed Au/multilayer system broadened to 1360–1740nm simultaneously with an appearance of the ∼15% transmission peak at 1.55μm. A preparation of similar metal/multilayer systems is one of the possible ways how to design the dielectric filters for near infrared region exploiting the good optical quality of the chalcogenide films and their simple deposition. [Copyright &y& Elsevier]

Abstract: The hydroxyl (OH−) impurities in germanium oxide (GeO2)-based glasses cause a strong absorption band between 2.4 and 3.6μm, which makes this region of the electromagnetic spectrum inaccessible for signal transmission. To eliminate the OH− absorption, PbF2 was employed by partially replacing the PbO content in the following compositions: 56GeO2−(31-x) PbO–9Na2O–4Ga2O3–xPbF2 (x =0, 3, 6, 9, 15, 25, 31). The removal of OH- ions in relation to the concentration of PbF2 incorporated in the glass-forming liquid was systematically studied. Differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy were respectively used for the analysis of glass devitrification and optical properties. The results of FTIR suggest that over 99% OH− impurity was removed, as compared to glasses without a purification process. An optimized core/cladding glass pair was then selected and the rod-in-tube technique was used. Fiber drawing conditions were established using the measured viscosity data and the devitrification range. The low OH− absorption fiber has demonstrated the transmission window up to 4μm with a loss of 2.34dB/m at 1.49μm. [Copyright &y& Elsevier]

Abstract: Windows for infrared sensors on missiles, aircraft and high energy laser systems must be of excellent spectral properties, high optical quality, large and durable enough to protect delicate sensors from harsh operating conditions. This paper describes work being done for IR window applications on heavy metal oxyfluoride (HMOF) glasses, which provide a combination of infrared transparency, strength, hardness, and environmental stability in a largely-sized formable material, and represents potential candidate materials for infrared windows. [Copyright &y& Elsevier]

In this paper we present some result on sol–gel derived silica–hafnia systems. In particular we focus on fabrication, morphological and spectroscopic assessment of Er3+-activated thin films. Two examples of silica–hafnia-derived waveguiding glass ceramics, prepared by top–down and bottom–up techniques are reported, and the main optical properties are discussed. Finally, some properties of activated microspherical resonators, having a silica core, obtained by melting the end of a telecom fiber, coated with an Er3+-doped 70SiO2–30HfO2 film, are presented. [Copyright &y& Elsevier]

Abstract: Three sets of boron nitride (BN) thin films are deposited with different N2/B2H6 flow ratios (r =4, 10 and 25) by plasma enhanced chemical vapor deposition (PECVD). The variations of physical properties in different deposition sets are analyzed by optical (XPS, FTIR, UV–visible spectroscopies), mechanical and electrical measurements. The films are considered to be deposited in a turbostratic phase (t-BN). Evolution of bonding configurations with increasing r is discussed. Relatively higher nitrogen flow rate in the source gas mixture results in lower deposition rates, whereas more ordered films, which tend to reach a unique virtual crystal of band gap 5.93eV, are formed. Anisotropy in the film structure and film inhomogeneity along the PECVD electrode radial direction are investigated. [Copyright &y& Elsevier]

Abstract: A quarter wave stack dielectric filter with normal incidence pass band in near-infrared range was prepared from alternating high index contrast chalcogenide films. The prepared filter consists of a low index Ge–S spacer layer surrounded by two 4.0 pairs Sb–Se/Ge–S reflectors. Films were deposited using flash and thermal evaporation techniques. After deposition, the filter was annealed at 165°C for 1h. Optical reflectivity measurements of the annealed filter revealed a ∼63% normal incidence passband near 1540nm. An ∼80% passband was recorded after illumination of the filter by the light with s-polarization at angles 35°, 45° and 55°, while its position shifted to 1451, 1476 and 1505nm, respectively. A ∼75% passband appeared near 1436, 1467 and 1498nm in response to illumination of the filter by the light with p-polarization at the same angles. The angular dependence of the reflectivity of dielectric multilayer can be exploited for filtering of incident light. [Copyright &y& Elsevier]

Abstract: A microstructured optical fibre based on an alumino-zirco-chloro-fluoride glass has been fabricated in which the light-guiding structure comprises a single ring of air-holes, machined directly into the preform rod using an ultrasonic drill around a large effective solid core. The objective was single-moded transmission of longer mid-infrared wavelengths at high laser power without causing radiation damage to the fibre material. It has been demonstrated that this fibre preserves high laser beam quality and can transmit wavelengths between 2.1 and 4.7μm, single-moded in an effective core of diameter 79μm. Optical fibre transmission losses from 1.4 to 10.3dBm−1 have been measured over this wavelength range. No damage was observed in the fibre at peak pulse power, setting a lower limit of >1GWcm−2 for the laser damage threshold. Brightness was preserved at wavelengths longer than 4μm. [Copyright &y& Elsevier]

Abstract: The synthesis optimization of three-dimensional photonic crystals (direct and inverse opals) is discussed in terms of the influence of processing parameters on the final optical quality. A colloidal/sol–gel route, starting with the self-organization of polystyrene microspheres into opal structures by convective self-assembly, followed by infiltration with a dielectric matrix precursor sol and heat treatment, has been followed. Several substrate hydrophilization methods have been tested and different substrates. Sol–gel infiltration of the opal template interstices with silica was achieved by dip-coating or micro-syringe application and it was followed by removal of the polymeric template. The concentration of the colloidal sol, containing polystyrene spheres of 235 or 460nm in diameter, was optimized. The structural and optical properties of the opals and inverse opals have been studied by field emission scanning electron microscopy and optical reflectivity spectroscopy, in order to assess the relationship between their structure and the photonic properties obtained. By using borosilicate glass substrates hydrophilized with hydrochloric acid, colloidal photonic crystals of good quality have been obtained, with well ordered regions up to ∼100μm2. By monitoring the effective refractive index change with relative humidity of the surrounding atmosphere, using spectroscopic ellipsometry with an environmental chamber, it was concluded that the present photonic crystals are suitable for humidity sensing applications. [Copyright &y& Elsevier]

Abstract: 95.8SiO2–4.2HfO2 planar waveguide activated by 0.2mol% Er and 0.2mol% Yb was fabricated by multi-target rf-sputtering technique. The optical parameters were measured by an m-line apparatus operating at 543.5, 632.8, 1319 and 1542nm. The waveguide compositions were investigated by energy dispersive spectroscopy. The waveguide exhibits a single propagation mode at 1.3 and 1.5μm with an attenuation coefficient of 0.2dB/cm at 1.5μm. The emission of 4I13/2 → 4I15/2 transition of Er3+ ion, with a 42nm bandwidth was observed upon TE0 mode excitation at 980 and 514.5nm. Photoluminescence excitation spectroscopy was used to obtain information about the effective excitation efficiency of Er3+ ions by co-doping with Yb3+ ions. Channel waveguide in rib configuration were fabricated by wet etching process in the active film. [Copyright &y& Elsevier]

Abstract: In this report we will show the changes of the band shape of the hydroxyl group (SiOH) infrared (IR) absorption band (∼3670cm−1) in silica glass induced by lowering temperature in the range from 290 to 20K. This band is considered as the overlap of several spectral components associated to the vibrational activity of hydroxyl groups in different bond configurations. By a suitable analysis of the experimental band profile in terms of different sub-bands, we studied the thermal evolution of each component and we reconsidered their assignations. For comparison we examined the SiOD absorption band (∼2710cm−1) as a function of temperature as well. Our data can be interpreted as an evidence of a conversion process of free into H(D)-bonded SiOH(D) groups. Moreover, we estimated the ratio between the molar extinction coefficients of the two main species involved in this process finding that this ratio is appreciably influenced by the isotopic exchange. [Copyright &y& Elsevier]

This paper presents the infrared characterization of methacrylic polymers containing heterocyclic azo dyes thin films using FTIR and Raman spectroscopies. The observed FTIR vibrational frequencies were analyzed and compared with theoretically predicted infrared spectra. The hybrid-type exchange-correlation potential of Becke, Lee, Yang and Paar (B3LYP) method and 6–311++G(d,p) basis set was applied to calculate polymers spectra. The computed IR spectra showed appreciable agreement with the experimental results. One can notice that the infrared properties of azo dyes polymers strongly depend on the type of substitution in the azobenzene moiety. Different substitution pattern in azobenzene moiety leads to significant changes in the spectrum. [ABSTRACT FROM AUTHOR]

Abstract: A study of the structure and bonding configuration of sol–gel silicate glasses by Raman and infrared spectroscopies is presented. Moreover, a review of the Raman lines and infrared bands assignment, the identification of the non-bridging silicon–oxygen groups and the ring structures are also demonstrated. The evolution of the changes of the bonding configuration in the composition and the stabilization temperature of the bioactive glasses is discussed in terms of the structural and textural characteristics of the glasses. Raman and infrared analyses contribute to the improvement in understanding of the local symmetry for sol–gel silicate glasses. infrared spectroscopy has allowed to identify the vibration bands of the hydroxyl groups associated with various configurations of the terminal silanol bonds on the glass surface and the free molecular water in the glass matrix. Raman analysis has provided an alternative method of quantifying the network connectivity grade and predicting the textural properties of the sol–gel silicate glasses. [Copyright &y& Elsevier]

Abstract: Studies on xRO·30Bi2O3 ·(70−x)B2O3 glasses have been carried out (0⩽ x ⩽30mol%, R=Zn, Ba). Elastic properties and Debye temperature have been investigated using sound velocity measurements at 4MHz. The ultrasonic parameters along with the IR spectroscopic studies have been employed to explore the role of divalent cations in the structure of the studied glasses. Analysis of infrared spectra indicates that RO is preferentially incorporated into the borate network, forming BO4 units. It is assumed that Bi2O3 enters the structure in the form of BiO6 only. The change of density and molar volume with RO content reveals that BO4 units linked to R2+ cations are denser than those linked to positive sites in the Bi2O3 network. Predicted values of four co-ordinated boron put forward questions about the reliability of assignment of structural units that Bi2O3 may form. [Copyright &y& Elsevier]

Abstract: Glasses of the system: xBi2O3–(100−x)B2O3 (x =20 to 66mol%) were prepared and characterized by density, DSC, UV–visible absorption and 11B MAS-NMR spectroscopy. Glass molar volume increases while the glass transition temperature decreases with Bi2O3 concentration. Densities of some bismuth borate glasses are found to be greater or very close to those of single crystal phases with equal composition. B11 MAS-NMR studies determined that the fraction of tetrahedrally coordinated borons (N 4) is maximum at 42mol% of Bi2O3 and that there is a local maxima in N 4 at Bi2O3 concentration of 50mol%. Glasses containing Bi2O3 concentration of 33mol% and higher show an unusual, intense absorption band just below the optical band gap. Two crystalline phases: Bi3B5O12 and Bi4B2O9 were prepared by devitrification of glasses and characterized by X-ray diffraction, FTIR and 11B MAS-NMR studies. Both crystalline phases contained significantly lower N 4 than glasses with equal composition. [Copyright &y& Elsevier]

Abstract: This paper describes the preparation and characterization of lithium fluoroalkylphosphate-containing composite polymer electrolyte based on a polyvinylidene fluoride–hexafluoropropylene (PVdF–HFP) matrix. A mixture of ethylene carbonate and diethyl carbonate was used as a plasticizing agent and nanoscopic Al2O3 as a filler. The membranes were characterized by ac impedance, SEM, DSC, FTIR and fluorescence. An electrolyte with 2.5wt% Al2O3 exhibited a conductivity of 9.8×10−4 Scm−1 at ambient temperature. It was found that filler contents above 2.5wt% rendered the membranes less conducting. [Copyright &y& Elsevier]

Abstract: We report on viscosity of a Ge17As18Se65 glass over the temperature range of 280–420°C and the successful co-extrusion and fiber-drawing of two chalcogenide glass boules to form a core/clad. pair. The co-extrusion produces a preform with optimum diameter stability and core/clad. glass ratio, and minimum defects at the core/clad. interface in the middle 120–200mm region of a 270mm long preform. Core/clad. fiber is drawn successfully from the extruded preform. An optical loss of 1.7dBm−1 at 1666cm−1 (6.0μm) and 6.7dBm−1 at 6649cm−1 (1.55μm) is reported. [Copyright &y& Elsevier]

Abstract: Multilayered Ge-based chalcogenide waveguides were fabricated on Si substrates by thermal evaporation. Channel waveguides were written in the core layer by inducing photoinduced changes in the refractive index by exposure to bandgap light. Very thin (∼20nm) Au islands were deposited on the top of the core layer for biological functionalization. FT-IR spectroscopy confirmed that the coating of the films with gold did not have a significant effect on the propagation and penetration of IR evanescent waves through the film. Self assembled monolayers (SAM) were formed on the gold islands via thiol chemistry for biological attachment. Antibody (human IgG, anti-E. coli O157:H7, and anti-Salmonella) complexes were formed on the Au islands via the SAMs. The films functionalized with anti-E. coli O157:H7 and anti-Salmonella antibodies were used to detect E. coli O157:H7 and S. enteriditis through label-free IR fingerprinting. Highly selective detection of bacterial targets was achieved at both the species (E. coli vs. S. enteriditis) and strain level (E. coli O157:H7 vs. E. coli K12). This mid infrared approach demonstrates the use of chalcogenides for biosensor. [Copyright &y& Elsevier]

Abstract: The kinetics of light-induced defect creation in a-Si:H is studied in early-time limit and as function of pre-existing defects of different thermal stability by electron spin resonance and optical spectroscopy techniques. Both for cw and for laser pulse exposures, the early-time kinetics follows sublinear t β time dependences, similar to the long-time limit. In addition, the overall defect creation rate is not a single function of the total defect number. Instead, it depends on the thermal stability, or annealing energy distribution, of the defects present in the film. Furthermore, creation of the thermally less stable defects is unaffected by the presence of a large number of stable defects introduced by pre-exposure at a higher temperature. These findings question the existing defect creation models. Thermal stability of the light-induced defects depends on the network microstructure, the less stable defects being created in a-Si:H deposited near microcrystalline transition. [Copyright &y& Elsevier]

Abstract: Silver was introduced into medieval glass by an ancient painting process using different clay minerals (ochre, illitic, montmorillonitic, and kaolinitic clays). The colorimetric properties, studied by UV–Vis spectroscopy, were dependent on the clay mineral as a result of different concentration of Ag ions diffused into the glass surface. TEM results showed the well known formation of silver nanoclusters which give the yellow coloration of the glass. The obtained results showed that clay properties such as specific surface area, pore volume and iron concentration (Fe2O3), are important factors that affect the yellow coloration. It is also observed that Fe2O3 acts as an oxidant agent for silver atoms providing the Ag2O formation. This oxide cannot diffuse into the glass structure and avoid the ion-exchanged process. After Ag ion diffusion some structural changes occur in the glass as it has been shown by Raman spectroscopy. It is observed that the diffusion process leads to depolymerization of the glass network as it is determined by analyzing the Qn components of Raman spectra. Two Raman bands at 148 and 244cm−1 assigned to Ag–O bonds can be associated to the presence of Ag2O on the glass painted surface. [Copyright &y& Elsevier]

Abstract: Glasses of the system: (70−x) TeO2 +15B2O3 +15P2O5 + xLi2O, where x =5,10,15,20,25 and 30mol% were prepared by melt quench technique. Dependencies of their glass transition temperatures (T g) and infrared (IR) absorption spectra on composition were investigated. It is found that the gradual replacement of oxides, TeO2 by Li2O, decreases the glass transition temperature and increases the fragility of the glasses. Also, IR spectra revealed broad weak and strong absorption bands in the investigated range of wave numbers from 4000 to 400cm−1. These bands were assigned to their corresponding bond modes of vibration with relation to the glass structure. [Copyright &y& Elsevier]

Abstract: In searching for new kind of photoelectric material, chalcogenide glasses in the GeS2–Sb2S3–CdS system have been studied and their glass-forming region was determined. The system has a relatively large glass-forming region that is mainly situated along the GeS2–Sb2S3 binary side. Thermal, optical and mechanical properties of the glasses were reported and the effects of compositional change on their properties are discussed. These novel chalcogenide glasses have relatively high glass transition temperatures (T g ranges from 566 to 583K), good thermal stabilities (the maximum of deference between the onset crystallization temperature, T c, and T g is 105K), broad transmission region (0.57–12μm) and large densities (d ranges from 2.99 to 3.34gcm−3). These glasses would be expected to be used in the field of rare earth doped fiber amplifiers and nonlinear optical devices. [Copyright &y& Elsevier]

Abstract: Chemical etching rates for two different chalcogenide glass compositions, As40S60 and As24S38Se38, were studied using sodium hydroxide based etchant solutions. Etching was performed using a variation of standard photolithographic masking and wet-etching techniques. Variations in etch rate with NaOH concentration and glass composition were observed. The depth of etch was characterized using an optical profilometer. Etch rate differences as large as three orders of magnitude between these two glasses were observed at low NaOH concentration (0.053M). We present a single variable etch rate curve of etch depth per time (nm/s) versus NaOH overall solution concentration (in M) for these two different chalcogenide glasses. This technology shows promise for fabricating photonic structures and has potential applications in fabricating novel photonic bandgap structures that will function in the long-wave infrared (LWIR) regime. [Copyright &y& Elsevier]

Abstract: We report the preparation of multilayers based on polyamide–imide polymer and As–Se or Ge–Se chalcogenide thin films. Chalcogenide films of As–Se and Ge–Se systems were deposited using a thermal evaporation method periodically alternating with spin-coated Polyamide–imide films. Fifteen layers of PAI+As–Se system and nineteen layers of PAI+Ge–Se system were coated. Optical properties of prepared multilayers have been established using UV–vis–NIR and Ellipsometric spectroscopy. Both, PAI+As–Se and PAI+Ge–Se multilayer systems, exhibited the high-reflection bands centered around 830nm and 1350nm, respectively. The shift of the band position of PAI+Ge–Se multilayers to lower energies was caused by higher thickness of Ge–Se films. The bandwidth of reflection band of 8 PAI+7 As–Se multilayer was ∼90nm while bandwidth of PAI+Ge–Se system decreased to ∼70nm because Ge–Se films have 0.1 lower refractive index against As–Se films. Design of 1D-photonic crystals based on alternating chalcogenide and polymer films is a new opportunity for application of chalcogenide thin films as optical materials for near-infrared region. [Copyright &y& Elsevier]

Glasses with 55–60mol% SnO and 40–45mol% P2O5 have shown extremely large differences in the chemical and thermal properties depending on the temperature at which they were melted. Glasses prepared at low melting temperature, 450–550°C, had low Tg, 150–200°C, and low chemical stability. Glasses prepared at high melting temperature, 800–1200°C, had much higher Tg, 250–300°C, and much higher chemical stability. No significant differences were found by 119Sn Mössbauer and 31P Nuclear Magnetic Resonance spectroscopy. Large differences in the OH-content could be detected as the reason by infrared absorption spectroscopy, thermal analyses, and 1H Nuclear Magnetic Resonance spectroscopy. In samples with low Tg, a broad OH – vibration band around 3000nm with an absorption intensity >20cm−1, bands at 2140nm with intensity ∼5cm−1, at 2038nm with intensity ∼2.7cm−1, and at 1564nm with intensity ∼0.4cm−1 were measured. These samples have shown a mass loss of 3–4wt% by thermal gravimetric analyses under argon in the temperature range 400–1000°C. No mass loss and only one broad OH-band with a maximum at 3150nm and low absorption intensity <4cm−1 could be detected in samples melted at high temperature, 1000–1200°C, which have much higher Tg, ∼300°C, and much higher chemical stability. [Copyright &y& Elsevier]

Abstract: The infrared absorption properties of a-SiC:H thin films dependence with the dc magnetron power density were investigated. The films were deposited in a mixture of CH4, H2 and Ar. The target used was polycrystalline Si. We found that the dc magnetron power density has an important contribution to the film composition. There is a strong dependence of the Si–H and Si–C bonds with the dc power density. [Copyright &y& Elsevier]

Abstract: A simple IR method of determining the fictive temperature of GeO2 glass, both surface and bulk, was developed using the same technique developed earlier for silica glass. Specifically, IR absorption and reflection peak wavenumbers of GeO2 structural bands were found to be correlated with the fictive temperature of the glass. Using this method structural relaxation kinetics can be investigated. Density and refractive index of GeO2 glass were also measured as a function of fictive temperature. [Copyright &y& Elsevier]

Abstract: The spectra of the real and imaginary components of the complex refractive index were determined for liquid n-propanol using a new method, which takes into account the dispersion of the refractive index in the visible range and requires integration over the entire absorption range in the near infrared, mid infrared and far infrared spectral regions. From these data the spectra of both components of the complex electric permittivity and complex polarizability of liquid n-propanol were determined in broad optical range (25000–350cm−1). Related high-frequency dielectric properties of the liquid were determined and discussed. The total molar polarization was also determined. The molar vibrational polarization related to various spectral ranges has been determined. It has been found to be extremely small for overtone bands. The main contribution stems from the deformation modes of the molecule and from the vibrations of the hydrogen-bonded OH group. The total molar vibrational polarization originating from internal vibrational modes in the 12000–350cm−1 region amounts to 2.45cm3 mol−1, contributing ca. 12.2% to the distortion polarization and 3.8% to the total molar polarization. [Copyright &y& Elsevier]

Abstract: Both surface and bulk fictive temperatures of chlorine-containing silica glass were measured using the IR method, after thermal, mechanical and chemical treatments. A metastable equilibrium state at 1200°C was first established for the glass by heat-treatment and a uniform fictive temperature was observed except for the sample surface created by polishing after the heat-treatment. The densified layer of the polished surface shifted the IR peak wavenumber, making the fictive temperature appear higher than the bulk. During the second heat-treatment at 950°C, the sample with the as-heat-treated surface and uniform fictive temperature of 1200°C developed non-uniform fictive temperature distribution with the bulk fictive temperature becoming lower than the surface fictive temperature. Usually, surface structural relaxation is faster than bulk structural relaxation and the surface fictive temperature becomes lower than the bulk fictive temperature when heat-treated at a lower temperature than the initial fictive temperature. The observed anomalous feature was attributed to chlorine volatilization from the glass surface layer creating a high viscosity surface layer. This conclusion was supported by the diffusion data of chlorine in the glass available in the literature. [Copyright &y& Elsevier]