Reflection spectra of silicate glasses in the vacuum ultraviolet region

Reflection spectra of silicate glasses were measured in the spectral region 2–13 eV. The bands due to bridging oxygen were found at 11.6 and 10.4–9.5 eV. The bands for non-bridging oxygens were found in the region 8.8–4.9 eV. They shift to lower energy with increasing ionic radius for the low valency cations while they shift to higher energy with increasing ionic radius for the high valency cations. The correlation between the measured bands and the absorption wavelength calculated from Drude-Voigt dispersion formula is discussed.     

Near Infrared Studies of Polymer Blends

Abstract

The dependence of absorption in the near-infrared region of cellulose acetate-polyaniline/camphorsulfonic acid blends on their conductivity and homogeneity has been studied. Thin films (10 to 100 μm) of the blends containing various amounts of protonated polyaniline show very high absorption in the NIR region. The absorption increases with increasing of conductivity and homogeneity of the sample.     

Infrared spectroscopic study of water in the hydrates of calcium nitroprusside: Ca[Fe(CN)5NO]·nH2O (n=1,4)

The infrared absorption bands due to the water molecules in calcium nitroprusside monohydrate and tetrahydrate were studied using partial deuteration and low-temperature techniques. An assignment of these bands based on the possible hydrogen bonds existing in the crystal lattice is proposed. Additional infrared spectroscopic data on the monohydrate and the anhydrous compound are included.Previous results of this work were presented at the 2nd Argentine Congress of Physical Chemistry, Córdoba, Argentina, September 1–5, 1980.     

Intrinsic and impurity infrared absorption in As2Se3 glass

A quantitative study of infrared absorption in the 250–4000 cm^?1 region of As₂Se₃ glasses doped with small amounts of As₂O₃ or purified by various procedures has been carried out with particular attention to absorption in the wavelength regions of the CO₂ and CO lasers. The dependence of the relative intensities of the oxide impurity bands in the 650–1340 cm^?1 region on the total amount of As₂O₃ added to the glass indicates the existence of three distinct oxide-impurity species. A number of higher-frequency impurity bands which are due to the presence of hydrogen in the glass and whose intensities are highly dependent on the glass-melting conditions have been observed and classified. Intrinsic multiphonon absorption in the 400–1100 cm^?1 region has been interpreted in terms of combination and overtone bands of the two highest-frequency fundamental vibrational modes. Absorption coefficients of As₂Se₃ glass in the 920–1090 cm^?1 CO₂ laser region are limited by intrinsic multiphonon absorption to values of around 10^?2 cm^?1. The lowest absorption coefficients measured in the 1700–2000 cm^?1 CO laser region were around 2 × 10^?3 cm^?1 and may contain contributions from hydrogen-impurity bands.     

Structural study of sol-gel silicate glasses by IR and Raman spectroscopies

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.     

Effect of Ammonia on Optical Absorption of Polyaniline Films

The influence of ammonia on the optical absorption of polyaniline films obtained by the electrochemical method is studied. In the presence of ammonia, the optical spectra of a polymer are found to change due to the appearance of a new absorption band with a maximum at 2.07 eV and a simultaneous decrease in the intensity of bands at 1.57 and 2.91 eV. The kinetics of changes showing the presence of an isobestic point at 2.71 eV is elaborated. The results can be used to optimize the ammonia gas sensors for monitoring the biotechnological processes in the food industry and the environment.     

Investigation of the optical properties of KGd(WO<Subscript>4</Subscript>)<Subscript>2</Subscript>:Nd<Superscript>3+</Superscript> crystals with allowance for absorption

The optical properties of a biaxial absorbing KGd(WO₄)₂:Nd³⁺ crystal have been investigated. The main refractive indices were measured in the visible spectral range and the absorption and transmission spectra of samples of these crystals were studied. The changes in the refractive indices were in the region of the absorption bands with the use of the Kramers-Kronig relation. Conoscopic pictures of this crystal in the regions of transparency and absorption bands were calculated and are presented.     

New intrinsic oxygen related defect bands in oxygen implanted silica

Type III silica samples were implanted with O using a multi-energy process that produced a layer of constant concentration to within ± 5% beginning ~ 80 nm from the surface and extending to ~ 640 nm below the surfaces of samples. The concentrations in the layer ranged from 0.035 atomic percent to ~ 2.1 atomic percent. The optical absorption was measured from 2 to 6.5 eV. The absorption due to the implanted ions was analyzed using the difference spectra of the various samples. These difference spectra showed that optical bands at ~ 4.7 eV, 5.35 eV, and ~ 6.2 eV were a primary result of O implantation. Based on these data, we attribute these bands to O-related centers. Comparison of the difference spectra of the O samples with those of Si samples implanted to approximately the same concentrations showed that bands at the three energies in the spectra of the O samples were not observed in the spectra of the Si samples. Based on the spin concentrations of peroxy radicals, spin concentrations of E′_γ, and optical absorption coefficients at 4.8-5.0 eV and at 5.83 eV, the oscillator strengths of the peroxy band (~ 4.8 eV) was estimated, from the oscillator strength of the absorption band at 5.83 eV to be < 0.014.     

Structure and spectroscopic properties of trapped holes in silica

We present the first consistent comparison of the theoretically predicted structures and spectroscopic characteristics of holes trapped in crystalline and amorphous silica. The structure and spectroscopic properties of Ge and [AlO₄]⁰ hole centers in α-quartz and self-trapped holes (STH₁ and STH₂) in silica glass were calculated using an ab initio embedded cluster method. The calculated principal values of g-tensor and hyperfine constants as well as the positions of maxima of optical absorption bands are in good agreement with the experimental data. In the case of Ge and [AlO₄]⁰ hole centers, as well as STH₁, the hole is almost fully localized on one O atom. In STH₂ the hole is delocalized over two bridging O atoms. The calculated principal values of the g-tensor and hyperfine constants of STH₁ and STH₂ support the assignment based on ESR studies. The calculated optical absorption energies of one-center holes in a amorphous silica agree with the experimentally observed absorption bands assigned to STH₁.     

Growth and Optical Properties of Tm:GdVO4 Single Crystal

Thulium-doped gadolinium vanadate (Tm:GdVO₄) single crystal has been successfully grown by a modified Czochralski (CZ) technique. Effective distribution coefficient of Tm was determined to be 0.74. Absorption characterization was performed in the 800 nm region and the maximum absorption peak was found at 799 nm for p polarization. Fluorescence spectra for tuning at the maximum absorption were obtained around 1.8-2.0µm region with 100 nm bandwidth. This suggests that a Tm:GdVO₄ crystal is expected as a new promising LD pumped solid-state laser in the 2µm region.     

Orthorhombic Site Symmetry of Cr3+ in ZnNH4PO4 6H2O Crystals

Spectroscopic investigations of Cr³⁺ doped ZAPH are carried out. From the nature of optical absorption bands and their splittings at the liquid nitrogen temperature, the site symmetry of the Cr³⁺ in ZAPH is attributed to orthorhombic distortion.     

Estimation of high and low UV intensity profiles of mesogenic oxovanadium (IV) salen complexes: Doubling effect of homologue number

This article estimates the high and low UV intensity profiles of mesomorphic oxovanadium (IV) salen [VO (4-C_nH_2n+1O)₂ salen; nVLC] complexes. Structure of these complexes have been optimized using the Density functional B3LYP with 6–31 + G (d) basis set using crystallographic geometry as input. The UV absorption spectral characteristics have been estimated in the UV region by employing the DFT method. The oscillator strength (f) and vertical transition energy (E_V) have been reported corresponding to absorption wavelength (λ_max). Further, some electrochemical properties have been reported for the molecule. The doubling effect of homologue number on the reported parameters has been discussed.     

Reflection spectra of various kinds of oxide glasses and fluoride glasses in the vacuum ultraviolet region

Reflection spectra of silicate, borate, phosphate, fluorophosphate and fluoride glasses are studied in the spectral region of 2–13 eV in order to understand their dispersion behaviors in the visible region from the point of view of atomic structures.The absorption bands due to bridging oxygen ions or fluorine ions are found at 11.6 eV and 10.4–9.5 eV in silicate glasses, at 10.2 and 8.8 eV in borate glasses, at 9.5 eV in phosphate glasses, at 11.2 eV in fluorophosphate glasses and at 11 eV in fluorozirconate glasses.In silicate glasses, the bands due to nonbridging oxygen ions are found in the region 8.8-4.9 eV. They shift to lower energies with increasing ionic radius, in the order of Ca²⁺, Sr²⁺ and Ba²⁺, for the glasses containing low valency cations, while they shift to higher energies with increasing ionic radius, in the order of Ti⁴⁺, Zr⁴⁺ and Th⁴⁺ or in the order of Nb⁵⁺ and Ta⁵⁺, for the glasses containing high valency cations.In glasses containing large amounts of PbO, strong bands due to PB²⁺ ions appear in the lower energy regions of 6.3–5.6 eV and 5.2–4.7 eV.     

Effect of gamma-rays on some mixed alkali borate glasses containing nickel

The change of optical absorption of some irradiated mixed alkali borate glasses containing nickel has been studied by varying the gamma-ray dose or the mixed alkali oxide content. The induced bands increase as the radiation process proceeds until a certain limit after which a constancy is assumed to be reached.The investigation of the observed spectra shows that there is an induced absorption band with its maximum at 550 nm, in addition to the characteristic absorption bands of the divalent nickel ions with peaks in the visible region at 410, 640, 680 and 750 nm.     

Absorption spectrum of Ge-doped silica samples and fiber preforms in the vacuum ultraviolet region

We report absorption measurements in the vacuum ultraviolet (VUV) spectral region on Ge-doped silica samples grown through chemical vapor deposition (CVD) and fiber preforms grown through modified chemical vapor deposition (MCVD) with GeO₂ doping concentration from 0.3 to 4.0 mol%. We observed in all spectra an absorption band at 5.15 eV and a structure at about 7.0 eV. We observed differences in the absorption spectrum between Ge-doped silica samples and fiber preforms in the shape and relative amplitude of optical absorption bands. The intensity of defect-related bands depends on the Ge concentration and distribution. Differences in Ge concentration and distribution are due to the preparation methods and growing conditions.     

掺钕KGW激光晶体的各向异性吸收光谱及其上转换发光

在室温下测量了掺钕钨酸钾钆(Nd3 ∶KGW)晶体三个晶轴方向的吸收光谱,其吸收谱带强度明显显示各向异性。将Judd-O felt(J-O)理论进行修正,使其扩展应用于处理各晶轴方向的吸收光谱,计算出三个晶轴方向的各光谱带吸收系数、电偶极跃迁振子强度,其结果说明了Nd3 :KGW吸收光谱存在着各向异性。同时还研究了该材料在812nm激发下的上转换荧光特性,观察到较强的蓝色荧光。     

Effects of composition and catalyst on the optical properties of ZrO2-based Ormosil films

FTIR spectroscopy measurements were performed to investigate zirconia-based Ormosil thin films. Samples synthesized with a sol-gel technique were prepared starting from 3-glycidoxypropil-trimethoxysilane (GLYMO) and zirconium(IV)-propoxide (Zr-OPr). Acetic or nitric acid were used as a catalyst. The effects induced by the Zr content and the catalyst type on the mid-infrared spectra of the sol-gel hybrid films were studied and a detailed assignment of the vibrational absorption bands is presented. The thermal evolution of the hybrid systems was also followed by monitoring the release of the organic groups, the thickness, and refractive index changes by means of FTIR, diffuse reflectance spectroscopy, and ellipsometry.     

Synthesis and optical properties of poly[4-methacryloxy-(4′-carboxy)-azobenzene]

Abstract

In the present work, the homopolymer built from the free radical polymerization of methacrylic monomer incorporating an azobenzene side-group has been synthesized and structurally characterized. The optical properties such as refractive index, extinction coefficient, absorption coefficient and optical energy band gap of poly[4-methacryloxy-(4′-carboxy)-azobenzene] thin film prepared by high vacuum sublimation method were determined using spectroscopic ellipsometry combined with transmittance measurements.

We found that in the spectrum of extinction coefficient there are absorption bands, which are assigned as the n-π* and π-π* electronic transitions of the azo compound.     

Energy spectrum of uranyl ions in soda-lime glass

The wide band structures observed in the absorption spectrum and the fluorescence spectrum induced by a broad-band light source are the superpositions of narrower bands associating with different non-interacting uranyl molecular systems in glass. When the uranyl molecular systems are selectively excited by narrow-band light sources, the bandwidths of the fluorescence decrease. Furthermore, fluorescence showed multiplet structures and shifting of these structures when the excitation wavelength was varied, particularly, between 5100 and 5250 Å. By means of selective excitation and correlation between excitation energy and fluorescence energy, the first absorption band in the visible region has been analyzed to be the superposition of six narrower bands.