Vibrational Spectroscopy of the Borate Mineral Priceite—Implications for the Molecular Structure

ABSTRACT

Priceite is a calcium borate mineral and occurs as white crystals in the monoclinic pyramidal crystal system. We have used a combination of Raman spectroscopy with complimentary infrared spectroscopy and scanning electron microscopy with Energy-dispersive X-ray Spectroscopy (EDS) to study the mineral priceite. Chemical analysis shows a pure phase consisting of B and Ca only. Raman bands at 956, 974, 991, and 1019 cm^?1 are assigned to the BO stretching vibration of the B₁₀O₁₉ units. Raman bands at 1071, 1100, 1127, 1169, and 1211 cm^?1 are attributed to the BOH in-plane bending modes. The intense infrared band at 805 cm^?1 is assigned to the trigonal borate stretching modes. The Raman band at 674 cm^?1 together with bands at 689, 697, 736, and 602 cm^?1 are assigned to the trigonal and tetrahedral borate bending modes. Raman spectroscopy in the hydroxyl stretching region shows a series of bands with intense Raman band at 3555 cm^?1 with a distinct shoulder at 3568 cm^?1. Other bands in this spectral region are found at 3221, 3385, 3404, 3496, and 3510 cm^?1. All of these bands are assigned to water stretching vibrations. The observation of multiple bands supports the concept of water being in different molecular environments in the structure of priceite. The molecular structure of a natural priceite has been assessed using vibrational spectroscopy.     

Bound Energy of Water in Hard Dental Tissues

Abstract

Enamel and dentin are composed, respectively, of 3 wt% and 10 wt% of water, which exhibits different features in the tissues: loosely and tightly bound water. The objective of this study is to clarify by infrared spectroscopy, the different features of the water in heated (100–1000°C) hard dental tissues (enamel and dentin). The water band between 3800 cm^?1 and 2500 cm^?1 was analyzed by infrared spectroscopy. The area dependence of the water band with temperature was compared with the Arrhenius equation in two regions (100–400°C and 700–1000°C). The activation energy was determined for these two regions, and similar values were observed for both tissues. For enamel we obtain ?4.1±0.2 kJ/mol at 100–400 °C and ?63±9 kJ/mol at 700–1000°C; for dentin ?4.1±0.2 kJ/mol at 100–400°C and ?60±11 kJ/mol at 700–1000°C. The water loss changes the color of the tissues, hydroxyapatite crystallographic parameters, and produce ESR signals. These changes were discussed and compared with the results observed in this work and after laser irradiation. We conclude that these two activation energies could be assigned to the adsorbed (loosely bound) and trapped (tightly bound) water.     

Vibrational Spectrometry Strategies for Quality Control of Procymidone in Pesticide Formulations

Abstract

Two vibrational spectrometry–based methodologies were developed for procymidone determination in wettable powdered pesticide formulations. The Fourier‐transform infrared (FTIR) procedure was based on the selective extraction of procymidone by chloroform and determination by peak area measurement between 1451 and 1441 cm^?1, using a baseline correction established between 1490 and 1410 cm^?1, and a precision of 0.4% and a limit of detection of 0.01% w/w procymidone for a sample mass of 25 mg were obtained. For FT‐Raman determination, the selected conditions were peak area measurement between 1005 and 995 cm^?1 Raman shift, with a baseline correction fixed between 1030 and 947 cm^?1, and a relative standard deviation of 1% and a limit of detection of 0.8% procymidone in the original sample were obtained. The sample frequency for FTIR determination was 30 hr^?1, lower than that for Raman with 40 hr^?1. FT‐Raman reduces to the minimum the reagent consumption and waste generation, also avoiding the sample handling and contact of the operator with the pesticide. It can be concluded that the proposed methods are appropriate for quality control in commercial pesticide formulations.     

Carbonization in boron-ion-implanted polymethylmethacrylate as revealed from Raman spectroscopy and electrical measurements

ABSTRACT

The results of Raman spectroscopy and electrical measurements of 40 keV boron-ion-implanted polymethylmethacrylate with ion doses from 6.25 × 10¹⁴ to 5.0 × 10¹⁶ ions/cm² are reported for the first time. The Raman spectra recorded in the 400–3800 cm^?1 range, showing the formation of new carbon–carbon bands for the as-implanted samples at higher ion doses (>10¹⁶ ions/cm²), are found to be an additional support for carbonization processes earlier revealed by slow positrons. The current–voltage dependences at 360 K testify also that the as-implanted samples examined with higher fluences (3.75 × 10¹⁶ and 5.0 × 10¹⁶ ions/cm²) have created a very thin conductive layer or conductive joints due to carbonization.     

Study on the effect of PEG in ionic transport for CMC-NH<Subscript>4</Subscript>Br-based solid polymer electrolyte

The present study investigates the ion transport properties and structural analysis of plasticized solid polymer electrolytes (SPEs) based on carboxymethyl cellulose (CMC)-NH₄Br-PEG. The SPE system was successfully prepared via solution casting and has been characterized by using electrical impedance spectroscopy (EIS), Fourier transform infrared (FTIR) spectroscopy, and x-ray diffraction (XRD) technique. The highest conductivity of the SPE system at ambient temperature (303 K) was found to be 1.12?×?10^?4 S/cm for un-plasticized sample and 2.48?×?10^?3 S cm^?1 when the sample is plasticized with 8 wt% PEG. Based on FTIR analysis, it shows that interaction had occurred at O–H, C=O, and C–O moiety from CMC when PEG content was added. The ionic conductivity tabulation of SPE system was found to be influenced by transport properties and amorphous characteristics as revealed by IR deconvolution method and XRD analysis.     

Poly(ethylene oxide)-lithium difluoro(oxalato)borate new solid polymer electrolytes: ion–polymer interaction,structural, thermal,and ionic conductivity studies

Solid polymer electrolytes based on high molecular weight poly(ethylene oxide) (PEO) complexed with lithium difluoro(oxalato)borate (LiDFOB) salt in various EO:Li molar ratios from 30:1 to 8:1 were prepared by using solution casting technique. Ion–polymer interaction, structural, thermal, and ionic conductivity studies have been reported by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarized optical microscopy (POM), differential scanning calorimeter (DSC), and impedance analysis. FTIR spectral studies suggested that the interaction of Li⁺ cations with the ether oxygen of PEO, where a triple peak broad band centered at 1105 cm^?1, corresponds to C–O–C stretching and extreme deformation occurs. XRD, POM, and DSC indicated that the inclusion of LiDFOB salt could reduce the crystallinity of PEO. The melting temperature of PEO shifted to lower temperature side by the addition of LiDFOB. The glass transition temperature obtained for the system 10:1 was ?38.2 °C. An increase in the ionic conductivity from 3.95?×?10^?9 to 3.18?×?10^?5 S/cm at room temperature (23 °C) was obtained through the addition of LiDFOB to a high molecular weight PEO. In addition, the ionic conductivity of the polymer electrolyte films followed an Arrhenius relation, and the activation energy decreased with increasing LiDFOB concentration.     

Structure comparison of Orpiment and Realgar by Raman spectroscopy

Raman spectroscopy was used to characterize and differentiate the two minerals, Orpiment and Realgar, and the bands related to the mineral structure. The Raman spectra of these two minerals are divided into three sections: (a) 100–250?cm^?1 region attributed to the sulfur–arsenic–sulfur bending vibrational modes; (b) 250–450?cm^?1 region due to the arsenic–sulfur stretching vibration; and (c) 450–850?cm^?1 region assigned to overtone and combination bands. A total of 14 Raman bands for the spectrum in the 1600–100?cm^?1 region were observed. The significant differences between the minerals Orpiment and Realgar are observed by Raman spectroscopy. Realgar shows the typical bands observed at 340, 268, 228, and 218?cm^?1, and the special bands at 379, 289, 200, 176, and 102?cm^?1 for Orpiment are observed. The additional bands in 850–450?cm^?1 region are only observed for the mineral Orpiment, which may be attributed to overtone and combination bands in the Raman spectrum. The variation in band positions is dependent upon the structural symmetry, arsenic–sulfur bond distances, and angles. Moreover, another cause for the difference is the effect of the intermolecular forces and to the strong coupling between close lying external and internal modes. The difference of these two minerals structure induce tremendous diversity on Raman spectra, so Raman spectroscopy offers the information on the molecular structure of the minerals Orpiment and Realgar.     

Raman Spectroscopic Study of the Copper Silicate Mineral Apachite Cu9Si10O29 · 11H2O

ABSTRACT

Apachite, Cu₉Si₁₀O₂₉ · 11H₂O, is a mineral named after the American Indian Apache tribe. Raman and infrared spectroscopy have been used to characterize the molecular structure of apachite. The structure of the mineral shows disorder, which is reflected in the difficulty in obtaining quality Raman spectra. Raman spectroscopy clearly shows the presence of OH units in the apachite structure, which attests the formula to be not correct. Both Raman and infrared spectroscopy show the presence of water in the apachite structure. Different water molecules are present with different hydrogen bonding strengths. A suggested formula might be Cu₉Si₁₀O₂₃(OH)₁₂ · 5H₂O.

The Raman band at 967 cm^?1 is assigned to the –SiO₃ symmetrical stretching vibration and the bands at 997 and 1096 cm^?1 are assigned to the ν₃ –SiO₃ antisymmetric stretching vibrations. An intense Raman band at 673 cm^?1 with a shoulder at 663 cm^?1 is assigned to the ν₄ Si-O-Si bending modes. Raman spectroscopy complemented with infrared spectroscopy enabled a better understanding of the molecular structure of apachite.     

The Translation Mechanism of Smectite to Illite: An Infrared Spectroscopic Study of Ordered Mixed-Layer Illite/Smecite

The infrared spectral characteristics of ordered mixed-layer illite/smectite interstratified clay mineral with different mixed-layer ratios (S% = 5%, 10%, 15%, 20%, 25%, and 30%, where S% is mixed-layer ratio) from the Shihezi Formation of Late Permian in the Hanxing mining area, Hebei province of China, were studied by infrared spectroscopy. The results show that three infrared regions (3625 cm^?1±, 1200–1000 cm^?1, 850–700 cm^?1) changed with S%'s variation. The characteristic absorption bands of smectite at 3640 cm^?1, 1030 cm^?1, and 825 cm^?1 disappeared gradually with the decrease of S%, and the intensity of characteristic absorption bands of illite at 3625 cm^?1, 1100 cm^?1, 1024 cm^?1, 796 cm^?1, and 777 cm^?1 increased. These changes indicated that the illitization of smectite was realized by partial substitution of aluminum iron (Al³⁺) for silicon iron (Si⁴⁺) in silico-oxygen (Si–O) tetrahedron.     

Infrared and Raman Spectroscopic Characterization of the Silicate Mineral Gilalite Cu5Si6O17 · 7H2O

Gilalite is a copper silicate mineral with a general formula of Cu₅Si₆O₁₇ · 7H₂O. The mineral is often found in association with another copper silicate mineral, apachite, Cu₉Si₁₀O₂₉ · 11H₂O. Raman and infrared spectroscopy have been used to characterize the molecular structure of gilalite. The structure of the mineral shows disorder, which is reflected in the difficulty of obtaining quality Raman spectra. Raman spectroscopy clearly shows the absence of OH units in the gilalite structure. Intense Raman bands are observed at 1066, 1083, and 1160 cm^?1.

The Raman band at 853 cm^?1 is assigned to the –SiO₃ symmetrical stretching vibration and the low-intensity Raman bands at 914, 953, and 964 cm^?1 may be ascribed to the antisymmetric SiO stretching vibrations. An intense Raman band at 673 cm^?1 with a shoulder at 663 cm^?1 is assigned to the ν₄ Si-O-Si bending modes. Raman spectroscopy complemented with infrared spectroscopy enabled a better understanding of the molecular structure of gilalite.     

Annealing of arsenic-and antimony-implanted silicon single crystals using A CW xenon arc lamp

Abstract

Continuous, incoherent light from a xenon arc lamp has been used to anneal radiation damage in <100> silicon single crystals produced by implantation of 30?keV arsenic or antimony ions to doses between 1×10¹⁵ cm^?2 and 1×10¹⁶ cm^?2. The recrystallized layers have been characterized by Rutherford-backscattering spectroscopy, ion-channeling, Transmission Electron Microscopy, and sheet-resistivity measurements.     

Synthesis and characterization of nanostructure hydrous iron–titanium binary mixed oxide for arsenic sorption

Synthesis of nanostructure hydrous iron–titanium binary mixed oxide (NHITBMO) had been reported by a simple method, and characterized by the X-ray diffraction (XRD), thermal analysis, transmission electron microscope (TEM), Föurier Transform Infrared (FTIR), surface area, and zero surface charge pH (pHzpc). The synthetic oxide was hydrated and microcrystalline with 77.8 m² g^?1 BET surface area. The particle size (nm) calculated using XRD peak table and TEM image was ~10–13 and 6–8, respectively. The pH_zpc value was 6.0 (±0.05) for the oxide. The NHITBMO showed pH dependent good sorption affinity for arsenic from the aqueous solution and, the Langmuir monolayer capacity (mg g^?1) was 80.0 and 14.6, respectively, for the As(III) and As(V). The pseudo-second order equation described the room temperature arsenic sorption kinetic data well. The minimum dose required was 1.6 g NHITBMO per L of water (As_total = 0.24 mg L^?1) to reduce the arsenic level below 0.01 mg L^?1 in batch treatment process.     

Modifications Induced by UV-Vis Irradiation on DNA Extract of Kiwifruit Investigated by Spectroscopic and Statistic Methods

ABSTRACT

Revealing molecular alterations induced on kiwifruit under UV-Vis irradiation requires a discussion of biochemical-cell infrared (IR) fingerprint (900 cm^?1–1800 cm^?1) bands characteristic of nucleic acids. FTIR-ATR spectroscopy and statistics and nondestructive methods for screening exposure effects induced by irradiation were used. There the irradiation influence on the main molecular bonds (i.e., ν(C-C), ν_s(PO₂?) and ν_as(PO₂?)) can be observed. Regression methods were used for statistical investigations. Two categories of variables were used: the absorbance measured at fixed wavenumber variables and the exposure dose. The bivariate correlations, partial correlations, and polynomial regression methods from SPSS were used for statistical investigations. The obtained results show that FTIR-ATR, in correlation with statistics techniques, might be useful to assess immediate radiation and oxidative-induced damage to nucleic acids. In this case IR spectroscopy can be used successfully to study conformational changes during DNA reversible denaturation especially on the sugar-phosphate vibrations domain.     

Investigation of L(+)-Ascorbic acid with Raman spectroscopy in visible and UV light

Abstract: Raman spectroscopy investigations of l(+)-ascorbic acid and its mono- and di-deprotonated anions (AH^? and A^2?) are reviewed and new measurements reported with several wavelengths, 229, 244, 266, 488, and 532 nm. Results are interpreted, assisted by new DFT/B3LYP quantum chemical calculations with 6-311++G(d,p) basis sets for several conformations of ascorbic acid and the anions. Raman spectra were measured during titration with NaOH base in an oxygen-poor environment to avoid fluorescence when solutions were alkaline. The ultraviolet (UV) absorption band for ascorbic acid in aqueous solution at ～247 nm was found to cause strong resonance enhancement for the ring C?C stretching mode (called B) at ～1692 cm^?1. The ascorbate mono-anion absorbs at ～264.8 nm giving Raman resonance enhancement for the same ring C–C bond stretching, downshifted to ～1591 cm^?1. Finally, for the ascorbate di-anion, absorption was found at ～298.4 nm with molar absorptivity of ～7,000 L mol^?1 cm^?1 and below ～220 nm. With UV light (244 and 266 nm), strongly basic solutions gave pronounced Raman resonance enhancement at ～1556 cm^?1. Relatively weak preresonance enhancement was seen for A^2? when excitation was done with 229 nm UV light, allowing water bands to become observable as for normal visible light Raman spectra.     

Changes in Dentin Collagen After Sample Grinding and Heating

ABSTRACT

Changes to the structure of the organic matrix of the dentin tissue were determined after sample grinding and heating. Powder dentin measuring 25–38 µm and slices with a thickness of about 50 µm were employed. Spectra acquisition was conducted with a Fourier-transform infrared spectrometer. The thermal treatment was performed between 100°C and 300°C, with steps of 25°C. After grinding, two bands (1283.5 ± 0.5 cm^?1 and 1240.7 ± 0.5 cm^?1) shifted to higher wavenumbers, while three bands (1339.5 ± 0.5 cm^?1, 1283.5 ± 0.5 cm^?1, and 1202.7 ± 0.5 cm^?1) shifted to lower wavenumbers after thermal treatment in the range 100–300°C; the band at 1283.5 ± 0.5 cm^?1 shifted only 2 cm^?1. Thermal treatment produced a wavenumber shift in the opposite direction compared with the shift produced after grinding. The observed changes in the vibration modes of the structure indicate that sample preparation or sterilization involving grinding and heating must be carefully evaluated in order to preserve the natural characteristic of the collagen structure.     

Broadly tunable quantum cascade laser in cantilever-enhanced photoacoustic infrared spectroscopy of solids

An external cavity quantum cascade laser (EC-QCL) is applied in the photoacoustic detection of solid samples. The EC-QCL used has a broad tuning range of 676 cm^?1 (970–1,646 cm^?1) in the mid-infrared region, which enables accurate broadband spectroscopy of large molecules. The high spectral power density of the EC-QCL is combined with an extremely sensitive optical cantilever microphone of the photoacoustic detector to achieve an ultimate sensitivity. The carbon black, polyethylene, and hair fiber samples were measured with the EC-QCL photoacoustic detection using electrical amplitude modulation to demonstrate the possibilities of the setup. The same measurements were repeated with a Fourier transform infrared (FTIR) spectrometer combined with a photoacoustic detector for a comparison. The EC-QCL photoacoustic setup yielded roughly a decade better signal-to-noise ratios than the FTIR setup with the same measurement time.     

An Infrared Method,with Reduced Solvent Consumption,for the Determination of Chlorsulfuron in Pesticide Formulations

A simple method has been developed for the determination of Chlorsulfuron in pesticide formulations by Fourier Transform Infrared (FTIR). Samples were diluted with CHCl_3^? , and the FTIR spectra of the samples and standards were obtained at a nominal resolution of 4 cm^? 1 from 4000 to 900 cm^? 1 with the accumulation of 25 scans. Chlorsulfuron determination was based on the measurement of peak area values from 1373 to 1363 cm^? 1 which were corrected by use of a two points baseline defined from 1401 to 1302 cm^? 1. The limit of detection achieved, which was of the order of 6 µg g^? 1, was appropriate for the determination of Chlorsulfuron in commercially available formulations. FTIR results were statistically comparable with those found by High Performance Liquid Chromatography (HPLC). The procedure reduces organic solvent consumption per sample to less than 3 ml CHCl₃, reduces waste generation and increases the sample measurement frequency up to 60 h^? 1.     

Optical and electrical properties of swift heavy ion beam-irradiated polycarbonate/polystyrene bilayer films

Polycarbonate/polystyrene bilayer films prepared by solvent-casting method were irradiated with 55 MeV carbon ion beam at different fluences ranging from 1×10¹¹ to 1×10¹³ ions cm^?2. The structural, optical, surface morphology and dielectric properties of these films were investigated by X-ray diffraction (XRD), UV–visible spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, optical microscopy and dielectric measurements. The XRD pattern shows that the percentage of crystallinity decreases while inter-chain separations increase with ion fluence. UV–visible spectroscopy shows that the energy band gap decreases and the number of carbon atoms in nanoclusters increase with the increase in ion fluences. The refractive index is also found to decrease with the increase in the ion fluence. Optical microscopy shows that after irradiation polymeric bilayer films color changes with ion fluences. The FTIR spectra evidenced a very small change in cross-linking and chain scissoring at high fluence. Dielectric constant decreases while dielectric loss and AC conductivity increase with ion fluences.     

A New FTIR Method for the Analysis of Low Levels of FFA in Refined Edible Oils

Abstract

This paper summarizes the application of stoichiometric analytical approaches to quantitative IR analysis and describes the development of a rapid and sensitive Fourier transform infrared (FTIR) method using such an approach for the determination of low levels (<0.005%) of free fatty acids (FFA) in refined edible oils. The method simply involves mixing the sample with methanol containing 2 g /L sodium carbodiimide (NaHNCN) on a vortex mixer for 30 s to convert the FFA to their salts, centrifuging the sample to separate the methanol phase containing the FFA salts from the oil, recording the FTIR spectrum of the upper methanol layer in a 100‐µm CaF₂ transmission flow cell, and ratioing this spectrum against that of the NaHNCN/methanol solution. The concentration of FFA salts is determined from the resulting differential spectrum by measurement of the v(COO^?) absorbance at 1573 cm^?1 relative to a reference wavelength of 1820 cm^?1. A calibration spanning the range 0–0.1% FFA (expressed as oleic acid) was devised by gravimetric addition of a defined, pure fatty acid to an acid‐free oil. Validation of the method by standard addition of palmitic acid to a variety of oils yielded an overall standard error of <±0.001% FFA. Comparison of triplicate FTIR and IUPAC titrimetric analyses of oils spiked with palmitic acid demonstrated that this FTIR method was more sensitive, accurate, and reproducible than the titration procedure, the latter having a significant positive bias of ～0.02%. Solvent/oil consumption in the FTIR method is 2 mL/10 g versus 150 mL/20 g for the titrimetric procedure. The FTIR method developed is particularly well suited for the determination of the low levels of FFA in refined oils but can readily be adapted with a simple adjustment of the oil/methanol ratio to cover FFA levels of up to 4.0%.     

Investigation of atmospheric {\text{O}}_{2}{\text{X}}{^{ 3}}{ \sum_{\text{g}}^{ - }} \,{\text{to}}\, {\text{b}}{^{ 1}}{ \sum_{\text{g}}^{ + }} using open-path tunable diode laser absorption spectroscopy

A tunable diode laser absorption spectroscopy (TDLAS) device fiber coupled to a pair of 12.5 in. telescopes was used to study atmospheric propagation for open path lengths of 100–1,000 meters. More than 50 rotational lines in the molecular oxygen A-band O₂ $ {\text{X}}{^{ 3}}{ \sum_{\text{g}}^{ - }} \,{\text{to}}\, {\text{b}}{^{ 1}}{ \sum_{\text{g}}^{ + }} $ transition near 760 nm were observed. Temperatures were determined from the Boltzmann rotational distribution to within 1.3 % (less than ±2 K). Oxygen concentration was obtained from the integrated spectral area of the absorption features to within 1.6 % (less than ±0.04 × 10¹⁸ molecules/cm³). Pressure was determined independently from the pressure-broadened Voigt lineshapes to within 10 %. A fourier transform interferometer (FTIR) was also used to observe the absorption spectra at 1 cm^?1 resolution. The TDLAS approach achieves a minimum observable absorbance of 0.2 %, whereas the FTIR instrument is almost 20 times less sensitive. Applications include atmospheric characterization for high energy laser propagation and validation of monocular passive raging.