IR Absorption Spectra Research Articles

Detection of germanium isotopes in biosynthesized Ge nanocrystals through different optical spectroscopy techniques

The current work aims to investigate the isotopic effect in biosynthesized Germanium nanocrystals (Ge NCs) through Raman and IR absorption spectra. By treating bulk germanium crystal with microorganisms in a weak magnetic field, Ge NCs with great chemical and isotopic purity are produced on its surface. Using various techniques, including X-ray diffraction, photoluminescence spectroscopy, micro-Raman spectroscopy, and FTIR spectroscopy, the structural and optical characteristics of the synthesized Ge NCs are studied. The PL, Raman, and IR peaks of synthesized material, which are recorded at various time intervals, are seen to have shifted. The PL peak shift of fabricated material is seen as a result of the quantum confinement effect. Raman and IR absorption spectra analysis, which are conducted at room temperature reveals the possible presence of germanium isotopes. It is observed that the phonon absorption peaks of synthesized germanium NC material shift to longer wavelengths with increasing average atomic mass of germanium. The observed optical properties of the synthesized Ge NCs have provided great help to study the change in structural and optical properties of the synthesized Ge crystal.

Quantitative evaluation of low-concentration OH impurities in quartz glass by infrared photothermal deflection spectroscopy

.Impurity control in materials is of great importance to achieve excellent performance, yet the quantitative determination of trace impurities, especially OH, is extremely difficult using today’s characterization techniques. Here we report the determination of trace amounts of OH in quartz glass plates by photothermal deflection spectroscopy (PDS) extended to the IR region. PDS detects trace OH based on the amount of heat generated during non-radiative processes during light irradiation. IR absorption spectra of quartz glasses with five different OH concentrations were investigated. In addition to the standard OH band around 3640 cm−1, we find that there are combination modes, overtones, and water-induced IR features. The presence and OH concentration dependence of these species reveal the role of impurities in quartz glass. The PDS is effective in quantifying OH concentrations below 1 ppmw (parts per million weight) in quartz glass plates.

Quantitative analysis of polar crystalline fractions in poly(vinylidene fluoride) electrospun fibers and electrosprayed films

We have used a novel technique, Fourier self-deconvolution (FSD) of the infrared spectrum, to quantify the relative fractions of the electro-active (EA) crystal phases in poly(vinylidene fluoride), PVDF. Electrospinning and electrospraying are effective methods to obtain the EA phases which include the polar β (chain conformation, TTTT) and γ (TTTGTTTG’) crystallographic phases. In this work we studied electrospun fiber mats and electrosprayed non-fibrous mats of PVDF obtained from solutions of N,N-dimethylacetamide and acetone. Wide-angle X-ray scattering (WAXS) and Fourier-transform infrared (FTIR) spectra show that samples prepared by electrospinning/electrospraying contained only polar crystal phases, and no non-polar alpha phase crystals were present. Fourier Self Deconvolution is a method used to synthetically narrow broad and complex infrared absorbance spectra. Here we demonstrate this technique to determine the relative fractions of β- and γ-phase crystals by resolving the peak at 840 cm−1 in the IR absorbance spectra. When the overall level of crystallinity is known, as it is here from X-ray analysis, then FSD allows determination of the absolute content of the polar β and γ phases. Comparing results from wide-angle X-ray scattering and FTIR/FSD, we show that γ-phase dominates over β-phase in both electrospun and electrosprayed materials, with relative γ to β ratios of 55/45 and 81/19, respectively.

IR Spectroscopy of Vacancy Clusters (Amber Centers) in CVD Diamonds Nanostructured by Fast Neutron Irradiation

We investigated the IR absorption spectra of CVD diamond damaged by fast neutrons (>0.1 MeV) with high fluences ranging from 1 × 1018 to 2 × 1019 cm−2 and annealed at temperatures of 200 °C to 1680 °C. After annealing above 1000 °C, the formation of “amber-centers” (ACs), associated with multivacancy clusters, is detected as deduced from the appearance of a strong absorption line at 4100 cm−1. Moreover, the concentration of the ACs in the irradiated diamond can be an order of magnitude higher than that observed previously in the darkest brown natural diamonds. A number of other absorption lines, including the H1b center at 4936 cm−1 (0.612 eV) and new lines at ~5700 cm−1 (0.706 eV) and 9320 cm−1 (1.155 eV) not reported before in the literature, are observed, and their intensity evolutions at annealing temperatures are documented. At the highest fluences, all the lines show reduced intensities and broadening and spectral shifts due to a very high defect concentration and partial amorphization. The obtained experimental data can be used for the analysis of defect generation, transformations and healing in irradiated synthetic and natural diamonds.

Tuning electronic structure and chemical reactivity via oxidation state in molybdenum oxide

Molybdenum oxide has a broad range of applications in areas such as catalysis, antimicrobial coatings, medicine, and sensors. In this study, we have investigated the geometric and electronic structure, thermal stability, and chemical reactivity of molybdenum oxide at different oxidation and electronic charge states using cluster models of Mo7On with density functional theory calculations. A decrease in the energy of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) has been identified as n increases from 0 to 21. Ionization potential and electron affinity of Mo7On correlate strongly with the energies of HOMO and LUMO, and both increase with increasing n. We have identified the most stable CO binding sites on Mo7On, calculated CO binding energy and simulated IR absorption spectrum of COMo7On. An n-dependent increase in CO stretching frequencies and decrease in CO binding energies indicate that electron backdonation from Mo7On to CO governs the changes in CO binding energy as a function of oxide composition. CO stretching frequency in COMo7O21 is 2197 cm−1, which is 55 cm−1 higher than in the gas phase CO molecule, indicating that CO is an electron density donor and the oxide acts as an electron acceptor at this stoichiometric composition. Comparing CO binding energies in neutral and ionic (q=+/-1) COMo7On, there is, in average, a stabilizing effect of excess (missing) charge on CO binding energy at low (high) n.

A disparity in solvatochromism of C[dbnd]O and S[dbnd]O vibrational probe: A study of structurally similar acetone and dimethyl sulfoxide

Solvatochromic studies of small IR probes are beneficialto study the structural dynamics of biomolecules as well as measuring the strength of surrounding electric fields in condensed phases.Herein, we have investigated the CO and SO vibrational probes of structurally similar acetone and dimethyl sulfoxide respectively to compare the solvatochromism. Interestingly in water CO formed both one hydrogen bond and two hydrogen bond complexes wherein SO formed only two hydrogen bond complexes.Not only this, but we have also investigated how different solvents alter the IR spectra of the CO and SO vibrating modes during the interaction with α CH of acetone and DMSO respectively.The IR absorption spectra of CO of acetone altered after αdeuteration(acetoned6) in aprotic organic solvents as well as aqueous solvents. But, surprisingly for DMSO and DMSOd6, the IR spectra of SO mode remain intact during α isotopic exchange (CH3to CD3) in organic aprotic solvents but in strong coordinating polar protic solvents (D2O) it is altered remarkably. The equivalent frequency gap of CO of acetone and acetoned6 in organic solvents and water represent the no interaction of α CH/D with solvent molecules. Parallelly unaltered IR spectral signature of SO of both DMSO and DMSOd6 in aprotic organic solvent represents the stationary state of the ‘S’ atom and altered SO IR absorption in water signifies the different α CH and α C-D interaction with the surrounding water molecules. These results are the cautionary of perturbation on IR probe during α CH interaction with solvents as well as guest molecules.

Almandine jewelry garnet from the Kitelya deposit (Karelia): composition and spectroscopic properties

Research subject. The chemical composition and spectroscopic properties of almandine jewelry garnets from the Kite-lya deposit in the Northern Ladoga region (Karelia). Materials and methods. The chemical composition, impurity elements, mineral inclusions and spectroscopic properties of almandine jewelry crystals were studied using IR and Mössbauer spectroscopy. Results. Garnet crystals were found to exhibit a weakly pronounced zonal composition, varying from Alm75Pir15Sps7Grs3 in the center to Alm80Pir14Sps4Grs2 at their edges. Therefore, the Ca and Mn contents decrease towards the grain edges. This zonality of garnets is characteristic of the processes of progressive metamorphism of their host rocks. The garnet crystals feature small inclusions of quartz, chlorite, mica FACI (biotite), ilmenite, rutile, monazite, zircon and pyrrhotite. The composition of chlorite, biotite and zircon was established. The parameter of the cube unit cell ao = 11.522 ± 0.003 Å was calculated. The IR absorption spectra of 995, 966, 901, 878, 638, 568, 528, 476 and 455 cm–1 are characteristic of the pyrope-almandine difference. Mössbauer spectroscopy revealed an insignificant admixture of trivalent iron (Fe3+) in the structure of Kitelya garnets (≈1 % of the amount of isomorphic iron). The obtained optical absorption spectra of garnet plates in the visible light spectrum indicate that Fe2+ ions in dodecahedral positions, to a lesser extent dodecahedral Mn2+ ions, as well as possibly octahedral Fe3+ ions are responsible for the bright red-crimson color of pyrop-almandine from the Kitelya deposit. Conclusions. A “portrait” of typomorphic features (composition and properties) of the pyrope-almandine jewelry garnet from the Kitelya deposit was obtained. This portrait can be used when analyzing the historical finds of faceted or cabochonized differences of almandine in jewelry, church utensils in both Russia and Europe (where this jewelry material was exported during the 17th century). The preservation of garnet jewelry differences in the host rock is due to the presence of thin amorphous kelefite shells or soft minerals (sericite, chlorite, kaolinite etc.).

Classification of Healthy and Cancer Colon Cells Grown on Glass Coverslip by Means of Fourier Transform Infrared Spectroscopy and Multivariate Methods

For several years, Fourier transform infrared (FTIR) microspectroscopy has been proving to be very promising for use in cytological diagnostics because of its capability of providing rapid and label-free biochemical information about cell samples. The adoption of FTIR as a clinical tool has been slowed because of the poor compatibility with cells deposited on glass slides, commonly used in clinical practice, because of the absorption of IR radiation by glassy materials in the 1000–1800 cm−1 spectral range. However, the possibility of also obtaining diagnostic information from the IR absorption spectra in the 2700–3700 cm−1 range (including few peaks related to vibrational modes in cell lipids and proteins) has recently emerged. In this work, we investigate the use of the FTIR technique in the 2700–3700 cm−1 range for diagnostic purposes about human colon cells grown on glass coverslips. In fact, using the principal components analysis (PCA) technique, we are able to discriminate FTIR spectra of healthy cells from those of cancerous ones, mainly due to the larger relative lipid content in the former compared to the latter. In addition, principal component analysis-linear discriminate analysis (PCA-LDA) and partial least square-discriminant analysis (PLS-DA) were used to build classification models for unknown FTIR spectra with optimal accuracy. These results support the promotion of the translation of the FTIR technique as a complementary diagnostic tool in cytological routine practice.

In English

We investigated influence of multiwalled carbon nanotubes (CNT) on spectral characteristics of composites “rubber-carbon nanotubes”on the base of butadiene-nitrile rubber at 0–10 % of CNTs. IR reflectance maxima of composites were measured in the spectral area of the rubber CH deformation and valence vibrations. IR absorption spectra of composites “rubber-carbon nanotubes” after vulcanization includes some giant two-polar oscillations. IR absorption spectrum of composites “rubber-carbon nanotubes” at 1 % of CNTs without vulcanization includes the alone two-polar oscillation. Two-photon interference is a result of quantum entanglement of dipole-active vibrations and photon splitting according to Hong-Ou-Mandel (HOM) quantum effect. Two-photon maximal entanglement saturation is called as Bell states. HOM quantum effect is perspective for high-coherent optical quantum computers on composites “rubber-carbon nanotubes”.

Gas mixtures IR absorption spectra decomposition using a deep neural network

An approach to multicomponent gas mixtures IR absorption spectra decomposition using a deep neural network was developed. The process of refinement and optimization of the absorption spectra data model to improve the accuracy of the inverse spectroscopic task solution is described. A criterion for the reliability of restoring the concentration of an individual component in a gas mixture based on its share of the area under the absorption spectrum curve was suggested and tested.

Electronic spectroscopy of trans-2-hexenal and 3-hexanol: Experimental and computational studies

Spectroscopic study of the absorption spectra of two green gases viz. trans-2-hexenal and 3-hexanol molecules by means of synchrotron radiation based photoabsorption and FTIR spectroscopy is presented. Quantum chemical calculations are used to compute the ground and excited state properties and correlate to the experimental results. From the IR spectra, vibrational assignments in the 600–3200 cm−1 region are made for the first time with the help of predicted fundamental frequencies at the optimized geometries for the molecule using DFT methodology. The electronic absorption spectra recorded in the 5.5–10 eV region for trans-2-hexenal consists of strong valence band at 6 eV followed by weak structures assigned to Rydberg series converging to the first two ionization potentials. While for 3-hexanol the electronic spectra lies entirely in the VUV region consisting of broad continuous absorption band above 7 eV. Vertical excited state energies are predicted using TDDFT calculations assist the assignments of the experimental electronic peaks to Rydberg and valence transitions. To get insights into the nature of the excited states potential energy curves of the first few excited states with respect to bond lengths and bond angles are studied. This work presents a first consolidated report of experimental and theoretical computation of photo absorption spectrum of trans-2-hexenal and 3-hexanol in the region IR and VUV absorption spectra.

Co2+, Ni2+ and Cu2+ complexes with phosphorylated derivatives of cyclen and diaza-18-crown-6: Effect of anion on the structure of complexes and their stability in solution

The effect of counterion A on the solid-state molecular structures and stability constants in solution for the complexes of the MA2 salts (M = Co2+, Ni2+, Cu2+, A = ClO4-, NCS-, NO3–) with phosphorylated cyclen and diaza-18-crown-6 derivatives has been studied. The synthesis, X-ray diffraction study, IR, and electronic absorption spectra of the complexes have been reported. The solid-state molecular structure of eight new complexes has been determined. The stability constants of the cobalt(II) complexes with 1,4,7,10-tetrakis[(diphenylphosphoryl)methyl]-1,4,7,10‑tetraazacyclododecane (L1) in acetonitrile have been estimated. A significant influence of the counterion of MA2 salt on the structure and stability of the complexes has been found. Salt anion affects both the number of formed complexes and the value of the stability constant of the complexes.

Experimental kinetic study of the reactions between OH radicals and three 2‐butenes over the temperature range 220–370 K and pressure range 0.67–40 kPa (5–300 Torr)

AbstractGas phase reactions between OH radicals and three 2‐Butenes were studied using a flash photolysis resonance‐fluorescence technique over the temperature range 220–370 K and total gas pressures of 0.67 kPa (5 Torr) to 40 kPa (300 Torr). Measured rate constants exhibited weak negative temperature dependences. Most studies were carried out in argon, but some test experiments employed helium or nitrogen as the bath gas. Rate constants of OH reactions with cis‐2‐butene and trans‐2‐butene were found to exhibit a pressure dependence at room temperature and above. Kinetic parameters and describing termolecular rate constants in Ar bath gas were derived for both reactions and can be used to calculate rate constants at the Earth's atmospheric conditions. The high‐pressure limiting rate constants are , cm3 molecule−1 s−1 and , cm3 molecule−1 s−1 for OH addition reactions with cis‐2‐butene and trans‐2‐butene, respectively. Their rate constants at 1 atm (760 Torr, 101 kPa) pressure can be represented as kZ(T, 1 atm) = 5.93 × 10−11 × (T/298)−1.61 × exp ( − 17/T), cm3 molecule−1 s−1 and kE(T, 1 atm) = 6.75 × 10−11 × (T/298)−1.64 × exp ( − 16/T), cm3 molecule−1 s−1. The rate constant of the OH addition reaction with 2,3‐dimethyl‐2‐butene was found to be pressure independent under our conditions and can be represented as kTME(T) = 14.08 × 10−11 × (T/298)−1.714 × exp ( − 95.7/T), cm3 molecule−1 s−1 with kTME (298 K) = (10.21 ± 0.30) × 10−11, cm3 molecule−1 s−1. Complementary measurements of IR absorption spectra of cis‐2‐butene and trans‐2‐butene were done between 500 and 3300 cm−1. They are presented in Supporting Information.

Indazole-derived synthetic cannabinoids: Absolute configuration determination and structure characterization by circular dichroism and DFT calculations

An increasing number of products containing synthetic cannabinoids pose a growing crisis to public health worldwide. Recently, a rising number of cases of serious adverse health effects, intoxications, and death cases associated with synthetic cannabinoids were reported. The current study represents the comprehensive structural analysis of three new synthetic cannabinoids (AB-, ADB- and AMB-FUBINACA) in solution investigated by electronic and vibrational circular dichroism together with the conventional methods of infrared and ultraviolet absorption spectroscopy, all supported by the density functional theory (DFT) calculations. The best level of theory to reproduce the experimental wavenumbers and wavelengths was found to be the B3PW91 method with a 6-311++G(d,p) basis set including the implicit solvent effect simulation. Very good agreement between the experimental and simulated spectra allowed us to determine the absolute configuration and a detailed interpretation of the IR absorption, VCD, ECD and UV spectra of AB-, ADB- and AMB-FUBINACA. In addition, the HOMO and LUMO electronic transitions were calculated.

Диагностика вредных примесей в водных средах с помощью спектроскопических методов и алгоритмов машинного обучения

The results of the development of a method for diagnosing 8-component aqueous solutions containing lithium, ammonium, iron (III), nickel, copper and zinc cations, as well as sulfate and nitrate anions, by IR absorption spectra and optical density spectra using artificial neural networks are presented. The application of artificial neural networks to the obtained arrays of spectroscopic data made it possible to ensure the simultaneous determination of the studied ions in a multicomponent mixture with an accuracy that satisfies the needs of environmental monitoring of natural and waste waters, as well as diagnostics of technological environments.

Исследование различий ИК-спектров дождевых червей как возможный способ их таксономической идентификации

IR spectrometry is successfully used for the taxonomic identification of various groups of invertebrates: butterflies, flies, grasshoppers, mosquitoes, weevils, and termites. Therefore, the purpose of this study was to assess the fundamental possibility of taxonomic identification of earthworms based on the study of the functional-group composition of their bodies by the method of IR-Fourier spectroscopy. Seven species of earthworms from five genera were the objects of the study: Aporrectodea caliginosa, Eisenia fetida, Eisenia nordenskioldi, Lumbricus rubellus, Rhiphaeodrilus diplotetrathecus, Octolasion lacteum, Eisenia ventripapillata. IR absorption spectra were registered on an FT-801 IR-Fourier spectrometer in the range of 500–4000 cm–1. The position, intensity, and area of the absorption bands were determined on all spectra. The maximum differences between individual species in intensity and position of protein and nucleic acid absorption bands were established. Using the principal component method, it was shown that the classification was based on the characteristics of the absorption bands of stretching and bending vibrations of methyl and methylene groups, as well as amide groups in the structure of worms. At the same time, the division of earthworms into subgroups with similar spectral characteristics could be explained by several reasons: their origin, kinship, and the influence of the environment. The data obtained during the study confirm the possibility of using IR spectrometry for the identification of earthworms.

Evolution of Structural and Spectral Characteristics of Lu-=SUB=-0.99-x-=/SUB=-Sm-=SUB=-x-=/SUB=-Eu-=SUB=-0.01-=/SUB=-BO-=SUB=-3-=/SUB=- orthoborates

The structure, IR absorption and luminescence spectra, and morphology of Lu0.99-xSmxEu0.01BO3 (0≤ x≤0.99) orthoborates synthesized at 970oC were studied. With an increase in the Sm3+ concentration, a successive change of five structural states is observed: calcite (0≤ x≤ 0.1)-> calcite + vaterite (0.1<x<0.3)-> vaterite (0.3≤ x≤ 0.95)-> vaterite + a triclinic phase (0.95<x≤ 0.98)-> a triclinic phase (0.98<x≤1). A wide range of Sm3+, concentrations at which the vaterite phase (0.3≤ x≤ 0.95) exists and a very narrow region of triclinic phase formation (0.98<x≤1) are important distinctive features of this system. Correspondence between the structure and spectral characteristics of these compounds was established. It is shown that the vaterite phase appears in the bulk of the microcrystals of the samples that have a calcite structure. Keywords: rare earth orthoborates, crystal structure, X-ray diffraction analysis, IR-spectroscopy, luminescence spectra.

Эволюция структурных и спектральных характеристик ортоборатов Lu-=SUB=-0.99-x-=/SUB=-Sm-=SUB=-x-=/SUB=-Eu-=SUB=-0.01-=/SUB=-BO-=SUB=-3-=/SUB=-

The structure, IR absorption and luminescence spectra, and morphology of Lu0.99xSmxEu0.01BO3 (0 ≤ x ≤ 0.99) orthoborates synthesized at 970°С were studied. With an increase in the Sm3+ concentration, a successive change of five structural states is observed: calcite (0 ≤ x ≤ 0.1) → calcite + vaterite (0.1 < x < 0.3) → vaterite (0.3 ≤ x ≤ 0.95) → vaterite + a triclinic phase (0.95 < x ≤ 0.98) → a triclinic phase (0.98 < x ≤ 1). A wide range of Sm3+ concentrations at which the vaterite phase (0.3 ≤ x ≤ 0.95) exists and a very narrow region of triclinic phase formation (0.98 < x ≤ 1) are important distinctive features of this system. Correspondence between the structure and spectral characteristics of these compounds was established. It is shown that the vaterite phase appears in the bulk of the microcrystals of the samples that have a calcite structure.

Investigation of electro-optical properties of gradient potassium niobate

The gradient perovskite material of potassium niobate is investigated in this work. As a result of the research, a gradient change in the properties was found: transformations of the IR absorption spectrum, the magnitude of the half-wave voltage depending on the composition of the grown potassium niobate crystal. The value of the half-wave voltage for plates cut from crystalline potassium niobate varied from 1500 to 1700 V with a change in the composition of potassium niobate in the range KxNb2-xO5-2x at x=0.9..1.

Изотопический сдвиг ИК полос поглощения монокристаллов германия

A clear correspondence between the position of the peak in the IR absorption spectrum of isotopically pure germanium single crystals and the mass number of the isotope was found. The dependence obtained can be used for express analysis of the mass composition of isotopically pure germanium single crystals.