Quantitative Raman spectroscopy: speciation of cesium silicate glasses

The silicate speciation forms an important aspect of the structure of silicate melts, a subject of interest to both the earth‐ and materials science communities. In this study, the Qⁿ speciation of binary cesium silicate glasses was studied by Raman spectroscopy. A method to extract the equilibrium constant from a set of Raman spectra is presented, and the least‐squares optimization algorithm is given (in Supporting Information). Log(K), the equilibrium constant of the speciation reaction, 2Q³ = Q⁴ + Q², equals −2.72 ± 0.11 at the glass transition. This extends the previously established correlation between log(K) and the inverse of the ionic radius of the network modifier to cesium. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural study of Mg‐bearing sodosilicate glasses by Raman spectroscopy

The presence of magnesium in glasses of geological, medical, and technological interests influences their physicochemical and durability properties. However, the understanding of the role of magnesium is dependent on the combined knowledge of the structural environment of magnesium in the glass or melt and of the silicate network connectivity of the studied systems. In this article, we present a Raman spectroscopic study of the network connectivity of 10 ternary silicate glasses in the system Na₂O MgO SiO₂ and one Mg‐free binary silicate glass Na₂O SiO₂. Results obtained at constant polymerization suggest the existence of various Qⁿ units according to the nature of the modifying cation. As polymerization decreases for Na₂O MgO αSiO₂ glasses (labeled as NMSα with α decreasing from 10 to 2), the band associated with Si O Si bending in fully polymerized region disappears being gradually replaced by a band attributed to Si O Si bending in region containing mainly Q² and Q³ species. For highly polymerized glasses (NMS10‐NMS4), the coexistence of these two bands suggests the presence of two interconnected networks. Concomitantly, the signal associated with Q³ species first increases. For a further decrease of the polymerization, the high wavenumber part of the signal associated with Q³ species decreases, while the intensity of the high wavenumber part of the band related to Q² species increases. This result strongly suggests that magnesium charge‐balances preferentially Q² species rather than Q³ species. Copyright © 2010 John Wiley & Sons, Ltd.     

Investigation of vanadium–sodium silicate glasses using XANES spectroscopy

X-ray absorption near edge structure spectroscopy has been used to investigate the electronic and atomic structure of (V₂O₅)_x(Na₂O)_0.30(SiO₂)_0.70−x (x < 0.1) glasses obtained by melt-quench technique. The results show no sign of metallic clustering of V atoms, but mixed oxidation states (+4 and +5) of V and strong V3d–O2p hybridization in the glasses. Detailed analysis has revealed that the glass samples contain about 15% V⁴⁺ and 85% V⁵⁺ and the ligand-field splitting is about 1.6 eV.     

Structural analysis of xCsCl(1−x)Ga2S3 glasses by means of DFT calculations and Raman spectroscopy

The alkali metal halide doping of gallium‐sulfide glasses yields improvements in the optical, thermal and glass forming properties. To understand these improvements, the short‐range order of xCsCl(1 − x)Ga₂S₃ glasses was probed by Raman spectroscopy. Raman spectra have been interpreted using density functional theory (DFT) harmonic frequency calculations on specific clusters of GaS₄H₄ and/or GaS₃H₃Cl tetrahedral subunits. The assignment of the observed vibrational bands confirms the main structural conclusions obtained with X‐ray and neutron diffraction experiments and gives some new insights into the gallium‐network present in the xCsCl(1 − x)Ga₂S₃ glasses. At the lowest concentration, the observed spectrum may be interpreted with small clusters such as dimers and trimers connected by corner‐sharing (CS) GaS₄H₄ tetrahedral subunits. The vibrational fingerprints of tri‐clusters with three‐fold coordinated sulfur atoms have also been identified; however, no Raman signature of chlorine‐doped subunits has been found to be caused by their insufficient intensity. For higher CsCl concentrations, distinct spectral features corresponding to chlorine‐doped clusters appear and are increasing in intensity with x. In other words, undoped and Cl‐doped tetrahedra coexist in the xCsCl(1 − x)Ga₂S₃ glasses. The added chlorine atoms induce a fragmentation of the glass network and replace the sulfur atoms in the CS tetrahedral environment. The comparison of the observed spectra with theoretical predictions and diffraction data favoured one‐fold coordinated chlorine atoms in the glass network. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural investigation of Te-based chalcogenide glasses using Raman spectroscopy

Structural changes of metals (Zn, Sb, In, Ga) and metal halides (AgI, ZnI₂, CdI₂, PbI₂, BiI₃) modified GeTe₄ glasses were investigated with the aid of Raman spectroscopy. The Raman spectra of these glasses in the frequency region between 100 cm^?1 and 300 cm^?1 display four main bands at about 124, 140, 159 and 275 cm^?1 which are contributed by Ge–Te, Te–Te, Te–Te and Ge–Ge vibration modes. The intensity of 159 cm^?1 and 275 cm^?1 bands vary with the addition of different glass modifiers. While the relative intensity of the 124 cm^?1 and 140 cm^?1 bands are insensitive to composition changes. Glass modifiers like Zn, In and Sb act as glass network unstabilizer which will disorganize the glass network by opening up the chain structures of Ge–Te and Te–Te. In the case of Ga and metal halides, Ga can open up Ge–(Te–Te)_4/2 tetrahedra and form Ga–(Te–Te)_3/2 triangle. Iodine can form covalent bonds with tellurium and decrease the tendency of microcrystal formation. Thus both Ga and iodine ultimately act as glass network stabilizer.     

The properties of GaMnN films grown by metalorganic chemical vapour deposition using Raman spectroscopy

An investigation of room-temperature Raman scattering is carried out on ferromagnetic semiconductor GaMnN films grown by metalorganic chemical vapour deposition with different Mn content values. New bands around 300 and 669 cm-1, that are not observed in undoped GaN, are found. They are assigned to disorder-activated mode and local vibration mode (LVM), respectively. After annealing, the intensity ratio between the LVM and E2 (high) mode, i.e., ILVM /IE2 (high) , increases. The LO phonon-plasmon coupled (LOPC) mode is found in GaMnN, and the frequency of the LOPC mode of GaMnN shifting toward higher side is observed with the increase in the Mn doping in GaN. The ferromagnetic character and the carrier density of our GaMnN sample are discussed.     

The properties of GaMnN lms grown by metalorganic chemical vapour deposition using Raman spectroscopy

An investigation of room-temperature Raman scattering is carried out on ferromagnetic semiconductor GaMnN films grown by metalorganic chemical vapour deposition with different Mn content values. New bands around 300 and 669 cm^-1, that are not observed in undoped GaN, are found. They are assigned to disorder-activated mode and local vibration mode (LVM), respectively. After annealing, the intensity ratio between the LVM and E₂(high) mode, i.e., I_LVM=I_E2(high), increases. The LO phonon-plasmon coupled (LOPC) mode is found in GaMnN, and the frequency of the LOPC mode of GaMnN shifting toward higher side is observed with the increase in the Mn doping in GaN. The ferromagnetic character and the carrier density of our GaMnN sample are discussed.     

Quantitative analysis of alcohol-water binary solutions using Raman spectroscopy

Raman spectroscopy was used for rapid and in situ measurements of alcohols in alcohol-water binary systems. An external standard was used to eliminate factors such as laser power or instrumental effects. Band ratios between the Raman bands of the target molecule and that of acetonitrile as external standard were calculated and found to be proportional to the mass fraction of alcohol. Better linearity was achieved as compared with that in the calibration curve obtained by plotting the Raman intensity alone. The equations of the calibration curves were y=0.2747x with R² of 0.9996 and y=0.2189x+1.340×10⁻³ with an R² of 1.000 in methanol-water and in ethanol-water binary systems, with y and x denoting the Raman intensity ratio and the mass fraction of alcohol, respectively.     

Identification of individual isotopes in a polymer blend using tip enhanced Raman spectroscopy

For the first time, tip enhanced Raman spectroscopy (TERS) blinking measurements are used to identify the individual isotopes of non‐Raman resonant polystyrene in a miscible, binary blend. This demonstrates the sensitivity and selectivity required for nanoscale chemical imaging and broadens the types of surface components potentially identifiable with TERS. Copyright © 2015 John Wiley & Sons, Ltd.     

Radiation-induced effects in soda-lime silicate glasses of different origin

Abstract

Correlated measurements of optical absorption and thermoluminescence of γ-irradiated soda-lime silicate (SLS) glasses were performed to detect and characterize the induced radiation damage in these materials. Three kinds of hole-type defect centers have been distinguished in glasses which differ with respect to the content of the glass-network modifiers and some multivalent transient metal cations. The main features of the related absorption bands are compared and discussed in terms of the purity and pre-irradiation history of samples.     

Forensic analysis of automotive paints by Raman spectroscopy

In this work, the possible contribution of Raman spectroscopy in forensic science is evaluated, more specifically for the analysis of automotive paint samples. Spectra from paint flakes as well as from cross sections were examined, in order to identify not only the pigments but also binders and extenders in all paint layers. Moreover, the possibility of distinguishing paint samples from different cars was evaluated to assess the use of vibrational spectroscopic techniques in the investigation of a hit-and-run accident. The presence of rutile and extenders, such as calcite and barium sulphate, could be demonstrated by their characteristic Raman bands. However, the identification of the binder by Raman spectroscopy was hampered: only with additional information from IR analysis could most of the bands in the spectrum be assigned to molecular vibrations of the binders. In contrast, organic pigments, having very distinctive and well-resolved characteristic bands, could easily be identified by comparing the spectra from the basecoat of the sample with spectra from a reference database. Because of these characteristic bands, the basecoat seems to provide the best spectra to distinguish paint samples. Moreover, some paints can also be distinguished by the absence or presence of the bands from calcium carbonate and barium sulphate in the primer surfacer. When recording spectra from paint flakes, Raman bands from the spectra of the clearcoat as well as from the basecoat are obtained. Copyright © 2005 John Wiley & Sons, Ltd.     

Structure of zinc-borate low-melting glasses derived from IR spectroscopy data

The IR spectra of glasses of the ZnO—SrO—B₂O₃ system with constant additions of PbO, Al₂O₃, and Li₂O (20 mol. % in sum) were studied. It is established that on replacement of B₂O₃ by ZnO, the structure of the glasses is characterized by the presence of groupings with the bridge bonds B^III— O—B^III, B^III—O—B^IV, B^IV—O—B^IV and end groups B^III— O⁻; ZnO practically exerts no influence on the coordination transition [BO₃] → [BO₄]. At a high content of ZnO, zinc ions are present in both a six-and a four-coordinated state. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 778–781, November–December, 2005.     

Luminescence spectroscopy of rare earth-doped oxychloride lead borate glasses

Ln-doped oxychloride lead borate glasses were studied using luminescence spectroscopy. Rare earth ions were limited to trivalent Pr³⁺, Tm³⁺, Eu³⁺ and Er³⁺. Luminescence spectra were registered, which correspond to ³P₀-³H₄ and ¹D₂-³H₄ transitions of Pr³⁺, ¹G₄-³H₅ and ¹G₄-³F₄ transitions of Tm³⁺, ⁵D₀-⁷F_J (J=0, 1, 2, 3, 4) transitions of Eu³⁺ and ⁴S_3/2,²H_11/2-⁴I_15/2 and ⁴I_13/2-⁴I_15/2 transitions of Er³⁺. Luminescence decays from the excited states of Ln³⁺ ions were analyzed in detail. The experimental results indicate that relatively high phonon energy of the host gives important contribution to the excited state relaxation of rare earth ions.     

Spectral properties of erbium-doped heavy metal oxyfluoride silicate glasses for broadband amplification

Erbium-doped glasses showing a wide 1.55μm emission band are reported in a novel heavy metal oxyfluoride glass system SiO_2－PbO－PbF_2 and their optical properties such as emission spectra, fluorescence lifetime and the refractive index have been investigated. The broad and flat {}^4I_{13/2}→{}^4I_{15/2} emission of Er^{3+} ions around 1.55μm can be used as host materials for potential optical amplifiers in wavelength-division-multiplexing network system. We find that with increasing PbF_2 content in the glass composition, the fluorescence full width at half maximum and fluorescence lifetime of the {}^4I_{13/2} level of Er^{3+} increase, while refractive index and density decrease.     

阳离子对硅酸盐玻璃激光拉曼光谱影响的研究

运用拉曼光谱技术研究了Na2O(K2O)—CaO(MgO)—SiO2,Na2O(K2O)—Al2O3—SiO2,Na2O(K2O)—B2O3—SiO2,Na2O(K2O)—PbO—SiO2和PbO—BaO—SiO2五个系统的玻璃。结果表明,阳离子对玻璃近程结构的改造会引起拉曼特征的变化。部分样品是根据古玻璃平均成分在实验室烧制的,这项研究对于运用激光拉曼光谱区分不同系统的古代硅酸盐玻璃有重要意义。     

Investigation of 1.3 μm emission in Nd-doped bismuth-based oxide glasses

Nd₂O₃-doped 43Bi₂O₃–xB₂O₃–(57−x)SiO₂–1.0Nd₂O₃ (x=57, 47, 39, 28.5, 19.5, 10, 0 mol%) bismuth glasses were prepared by the conventional melt-quenching method, and the Nd³⁺: ⁴F_3/2→⁴I_13/2 fluorescence properties had been studied in an oxide system Bi₂O₃–B₂O₃–SiO₂. The Judd–Ofelt analysis for Nd³⁺ ions in bismuth boron silicate glasses was also performed on the basis of absorption spectrum, and the transition probabilities, excited-state lifetimes, the fluorescence branching ratios, quantum efficiency and the stimulated emission cross-sections of ⁴F_3/2→⁴I_13/2 transition were calculated and discussed. The stimulated emission cross-sections of 1.3 μm were quite large due to a large refractive index of the host. Although the effective bandwidths decreased with increasing SiO₂ content, quantum efficiencies and stimulated emission cross-sections enhanced largely with increasing SiO₂ content.     

Chemical and isotopic analysis using diode laser spectroscopy: applications to volcanic gas monitoring

We report on a diode-laser-based spectrometer, operating at a wavelength of 2 μm, which enables for simultaneous measurements of CO₂ and H₂O concentrations in gaseous mixtures with high precision and accuracy. We implemented the very simple approach of a direct measurement of absorption in a multiple reflection cell with a pathlength of 50 m. Gas concentration is simply retrieved from the integrated absorbance, without using calibration cells. The spectrometer is equipped with single-mode optical fibers in order to probe remote environments. The possible application in volcanic areas will be discussed. We also investigated the possibility to measure the isotopic ratio ¹³CO₂/¹²CO₂, which is another relevant parameter for monitoring volcanic activity.     

γ辐照对掺Er硅酸盐玻璃吸收和发光特性的影响

用传统的高温熔融法熔制了一系列掺Er硅酸盐玻璃, 并测试了这些样品经5 kGy γ 射线辐照前后紫外至近红外的吸收和荧光光谱. 实验结果表明, 辐致暗化效应使得玻璃材料中形成了大量色心, 导致在400 nm附近出现强吸收带, 其尾端延伸至近红外区. 辐照产生的新能带增加了基质与Er³⁺ 特定能级(如²H_11/2, ⁴S_3/2及⁴F_9/2等) 之间的能量传递, 从而使辐照后的样品荧光寿命减小, 且在相同激发条件下荧光强度下降. 室温下辐照样品在荧光测试过程中出现了漂白现象.     

Laser spectroscopy of Nd and Dy ions in lead borate glasses

The spectroscopic and laser properties of Nd³⁺ and Dy³⁺ ions in lead borate glass were studied. Luminescence spectra recorded in the near-infrared and visible ranges correspond to ⁴F_3/2-⁴I_J/2 (J=9, 11, 13) transitions of Nd³⁺ and ⁴F_9/2-⁶H_J/2 (J=11, 13, 15) transitions of Dy³⁺, respectively. Luminescence decay curves were analyzed as a function of activator concentration. Luminescence quenching is observed, which is due to Ln-Ln interaction increasing. Several spectroscopic parameters relevant to laser potential of Ln³⁺ ions (Ln=Nd, Dy) in lead borate glass were determined. The relatively large values of the quantum efficiency and the room-temperature emission cross-section for the ⁴F_3/2-⁴I_11/2 transition of Nd³⁺ at 1061 nm and the ⁴F_9/2-⁶H_13/2 transition of Dy³⁺ at 573 nm imply that Ln-doped lead borate glasses can be considered as promising solid-state materials for laser applications.     

Elucidation of the crystallization kinetics for sodium-alumino-silicate glasses containing different amounts of manganese oxide

The glass samples [40SiO₂?+?5Al₂O₃?+?{55???x}Na₂O?+?xMnO₂] where x?=?0.05, 0.2, 0.4, 0.6, 0.8, and 1?mol% MnO₂ before and after being heat treated were subjected to X-ray diffraction. The diffraction lines provided clear evidence of the nucleation and growth, which are characteristic of sodium silicate phase. Crystallization studies were conducted using differential thermal analysis. Crystallization peak temperatures were identified and the transformed fractions were determined. Both the rate of growth, K ₀, and the activation energy, E, depend on the influence of manganese ions in the glass network as a modifier or as a former and the manganese content. The values of the Avrami parameter, n, were calculated using two methods and were in excellent agreement. The process of nucleation and growth rate depends on the manganese content.