Search

H3BO3 was used as the sintering additive to enable Zn0.997Cu0.003ZrNb2O8 ceramics to accomplish low‐temperature sintering and outstanding microwave dielectric performances. Composite ceramics were created using typical solid‐state processes. The effects of added H3BO3 on the sintering behavior, microstructural characteristics, vibrational properties, and microwave dielectric performances of Zn0.997Cu0.003ZrNb2O8 + x wt% H3BO3 (2 ≤$ \le $ x ≤$ \le $ 8) ceramics have been systematically investigated by means of X‐ray diffraction, Raman scattering spectroscopy, scanning electron microscopy, and complex chemical bond theory. The results of relative density and microscopic morphology demonstrated that the application of an adequate quantity of H3BO3 additive can significantly enhance sintering properties. The doped H3BO3 alters the inter‐ionic interactions so that the structural features become intrinsic to the microwave dielectric performances. The particularly satisfactory microwave dielectric performances (εr${\varepsilon }_r$ = 10.61, Q×f$ Q \times f $ = 33 980 GHz, and τf${\tau }_f$ = ‐45.10 ppm/°C) were detected in x = 6 ceramic specimens sintered at 950°C, which would make it promising for use in modern low temperature co‐fired ceramics technology. [ABSTRACT FROM AUTHOR]

Raman spectroscopy, a non-destructive analytical technique, provides information about the structure and composition of substances. It has been widely applied in the fields of chemistry, biology, and materials science for analysis and research. Through three years of pedagogical development, our instructional design for Raman scattering spectroscopy experiment has accumulated considerable practical experience. This experimental course is structured around three segments: qualitative, quantitative, and trace analysis, initiating with the intriguing task of distinguishing between authentic and counterfeit jadeite—a familiar challenge that ignites students’ curiosity and eagerness to delve into Raman spectroscopy. Utilizing portable Raman spectrometer enables students to gain an understanding of the instrument's construction and functionality, while mastering the fundamental concepts of Raman spectroscopy and its surface-enhanced variant. This educational venture equips students with the proficiency to adeptly conduct Raman spectroscopic analyses on solid and liquid samples, as well as trace substances, thus establishing a solid foundation for their mastery of related spectroscopy analysis courses. [ABSTRACT FROM AUTHOR]

The lattice dynamical properties of dilute InAs1−xNx/InP (001) epilayers (0 ≤ x ≤ 0.03) grown by gas-source molecular beam epitaxy were carefully studied experimentally and theoretically. A high-resolution Brüker IFS 120 v/S spectrometer was employed to measure the room-temperature infrared reflectivity (IRR) spectra at near-normal incidence (θi = 0). The results in the frequency range of 180–500 cm−1 revealed accurate values of the characteristic In-As-like and In-N-like vibrational modes. For InAs1−xNx alloys, a classical "Drude–Lorentz" model was constructed to obtain the dielectric functions ε ~ ω in the far IR regions by incorporating InAs-like and InN-like transverse optical ω T O modes. Longitudinal optical ω L O phonons were achieved from the imaginary parts of the simulated dielectric loss functions. The theoretical results of IRR spectra for InAs1−xNx/InP (001) epilayers using a multi-layer optics methodology provided a very good agreement with the experimental data. At oblique incidence (θi ≠ 0), our study of s- and p-polarized reflectance (Rs,p(ω)) and transmission (Ts,p(ω)) spectra allowed the simultaneous perception of the ω T O and ω L O phonons of the InAs, InN and InAs0.97N0.03 layers. Based on the average t-matrix Green's function theory, the results of local vibrational modes for light S i I n + donors and S i A s − ,   C A s − acceptors in InAs were found in good agreement with the existing Raman scattering and infrared spectroscopy data. I n I n N , however, the method predicted an in-band mode for the M g I n − acceptor while projecting an impurity mode of the S i I n + donor to appear just above the maximum ω m a x I n N [ ≡ 595   c m − 1 ] phonon frequency region. In InAs1−xNx/InP (001) epifilms, the comparison of reflectivity/transmission spectra with experiments and the predictions of impurity modes for isoelectronic donor and acceptor impurities in InAs and InN can be valuable for appraising the role of defects in other technologically important semiconductors. [ABSTRACT FROM AUTHOR]

Experimental and theoretical assessments of phonon and optical characteristics are methodically accomplished for comprehending the vibrational, structural, and electronic behavior of InP1−xSbx/n-InAs samples grown by Gas-Source Molecular Beam Epitaxy. While the polarization-dependent Raman scattering measurements revealed InP-like doublet covering optical modes ( ω L O I n P ~ 350 cm−1, ω T O I n P ~ 304 cm−1) and phonons activated by disorders and impurities, a single unresolved InSb-like broadband is detected near ~195 cm−1. In InP1−xSbx, although no local vibrational (InSb:P; x → 1) and gap modes (InP:Sb; x → 0) are observed, the Raman line shapes exhibited large separation between the optical phonons of its binary counterparts, showing features similar to the phonon density of states, confirming "two-mode-behavior". Despite the earlier suggestions of large miscibility gaps in InP1−xSbx epilayers for x between 0.02 and 0.97, our photoluminescence (PL) results of energy gaps insinuated achieving high-quality single-phase epilayers with x ~ 0.3 in the miscibility gap. Complete sets of model dielectric functions (MDFs) are obtained for simulating the optical constants of binary InP, InSb, and ternary InP1−xSbx alloys in the photon energy (0 ≤ E ≤ 6 eV) region. Detailed MDF analyses of refractive indices, extinction coefficients, absorption and reflectance spectra have exhibited results in good agreement with the spectroscopic ellipsometry data. For InP0.67Sb0.33 alloy, our calculated lowest energy bandgap E0 ~ 0.46 eV has validated the existing first-principles calculation and PL data. We feel that our results on Raman scattering, PL measurements, and simulations of optical constants provide valuable information for the vibrational and optical traits of InP1−xSbx/n-InAs epilayers and can be extended to many other technologically important materials. [ABSTRACT FROM AUTHOR]

The long-range crystallographic order and anisotropy in β-(AlxGa1−x)2O3 (x = 0.0, 0.06, 0.11, 0.17, 0.26) crystals, prepared by optical floating zone method with different Al composition, is systematically studied by spatial correlation model and using an angle-resolved polarized Raman spectroscopy. Alloying with aluminum is seen as causing Raman peaks to blue shift while their full widths at half maxima broadened. As x increased, the correlation length (CL) of the Raman modes decreased. By changing x, the CL is more strongly affected for low-frequency phonons than the modes in the high-frequency region. For each Raman mode, the CL is decreased by increasing temperature. The results of angle-resolved polarized Raman spectroscopy have revealed that the intensities of β-(AlxGa1−x)2O3 peaks are highly polarization dependent, with significant effects on the anisotropy with alloying. As the Al composition increased, the anisotropy of Raman tensor elements was enhanced for the two strongest phonon modes in the low-frequency range, while the anisotropy of the sharpest Raman phonon modes in the high-frequency region decreased. Our comprehensive study has provided meaningful results for comprehending the long-range orderliness and anisotropy in technologically important β-(AlxGa1−x)2O3 crystals. [ABSTRACT FROM AUTHOR]

The lattice dynamical properties of dilute InAs1−xNx/InP (001) epilayers (0 ≤ x ≤ 0.03) grown by gas-source molecular beam epitaxy were carefully studied experimentally and theoretically. A high-resolution Brüker IFS 120 v/S spectrometer was employed to measure the room-temperature infrared reflectivity (IRR) spectra at near-normal incidence (θi = 0). The results in the frequency range of 180–500 cm−1 revealed accurate values of the characteristic In-As-like and In-N-like vibrational modes. For InAs1−xNx alloys, a classical “Drude–Lorentz” model was constructed to obtain the dielectric functions ε~ω in the far IR regions by incorporating InAs-like and InN-like transverse optical ωTO modes. Longitudinal optical ωLO phonons were achieved from the imaginary parts of the simulated dielectric loss functions. The theoretical results of IRR spectra for InAs1−xNx/InP (001) epilayers using a multi-layer optics methodology provided a very good agreement with the experimental data. At oblique incidence (θi ≠ 0), our study of s- and p-polarized reflectance (Rs,p(ω)) and transmission (Ts,p(ω)) spectra allowed the simultaneous perception of the ωTO and ωLO phonons of the InAs, InN and InAs0.97N0.03 layers. Based on the average t-matrix Green’s function theory, the results of local vibrational modes for light SiIn+ donors and SiAs−, CAs− acceptors in InAs were found in good agreement with the existing Raman scattering and infrared spectroscopy data. InInN, however, the method predicted an in-band mode for the MgIn− acceptor while projecting an impurity mode of the SiIn+ donor to appear just above the maximum ωmaxInN[≡595 cm−1] phonon frequency region. In InAs1−xNx/InP (001) epifilms, the comparison of reflectivity/transmission spectra with experiments and the predictions of impurity modes for isoelectronic donor and acceptor impurities in InAs and InN can be valuable for appraising the role of defects in other technologically important semiconductors.

Experimental and theoretical assessments of phonon and optical characteristics are methodically accomplished for comprehending the vibrational, structural, and electronic behavior of InP1−xSbx/n-InAs samples grown by Gas-Source Molecular Beam Epitaxy. While the polarization-dependent Raman scattering measurements revealed InP-like doublet covering optical modes (ωLOInP~350 cm−1, ωTOInP~304 cm−1) and phonons activated by disorders and impurities, a single unresolved InSb-like broadband is detected near ~195 cm−1. In InP1−xSbx, although no local vibrational (InSb:P; x → 1) and gap modes (InP:Sb; x → 0) are observed, the Raman line shapes exhibited large separation between the optical phonons of its binary counterparts, showing features similar to the phonon density of states, confirming “two-mode-behavior”. Despite the earlier suggestions of large miscibility gaps in InP1−xSbx epilayers for x between 0.02 and 0.97, our photoluminescence (PL) results of energy gaps insinuated achieving high-quality single-phase epilayers with x ~ 0.3 in the miscibility gap. Complete sets of model dielectric functions (MDFs) are obtained for simulating the optical constants of binary InP, InSb, and ternary InP1−xSbx alloys in the photon energy (0 ≤ E ≤ 6 eV) region. Detailed MDF analyses of refractive indices, extinction coefficients, absorption and reflectance spectra have exhibited results in good agreement with the spectroscopic ellipsometry data. For InP0.67Sb0.33 alloy, our calculated lowest energy bandgap E0 ~ 0.46 eV has validated the existing first-principles calculation and PL data. We feel that our results on Raman scattering, PL measurements, and simulations of optical constants provide valuable information for the vibrational and optical traits of InP1−xSbx/n-InAs epilayers and can be extended to many other technologically important materials.

Micro Raman tomographic imaging (mRTI) is an excellent measurement technique that can nondestructively measure and image the fracture state of the crystal lattice inside materials with a high spatial resolution. mRTI has been successfully used for translucent materials such as wide bandgap semiconductor wafers. The applicability of this measurement method was evaluated by observing the wear damage in polycrystalline industrial ceramics materials. The influence of optical diffusion on the surface and inside of polycrystalline materials is a concern for the internal measurements by the optical beam. The quality degradation of spectral signals due to disturbances in the optical beam was confirmed by mRTI measurements on a commercial alumina plate. The application of surface polishing treatment was attempted to reduce the influence of surface optical diffusion. Three kinds of the surfaces were observed by mRTI, as the initial surface of the alumina plate, polished with #400 and #800 diamond abrasive lapping film, respectively. It was confirmed that the effective measurement depth range can be extended by reducing the surface roughness. However, we confirmed that excessive surface polishing may overwrite the damage on the measurement surface, making it difficult to observe the original damage.

The long-range crystallographic order and anisotropy in β-(AlxGa1−x)2O3 (x = 0.0, 0.06, 0.11, 0.17, 0.26) crystals, prepared by optical floating zone method with different Al composition, is systematically studied by spatial correlation model and using an angle-resolved polarized Raman spectroscopy. Alloying with aluminum is seen as causing Raman peaks to blue shift while their full widths at half maxima broadened. As x increased, the correlation length (CL) of the Raman modes decreased. By changing x, the CL is more strongly affected for low-frequency phonons than the modes in the high-frequency region. For each Raman mode, the CL is decreased by increasing temperature. The results of angle-resolved polarized Raman spectroscopy have revealed that the intensities of β-(AlxGa1−x)2O3 peaks are highly polarization dependent, with significant effects on the anisotropy with alloying. As the Al composition increased, the anisotropy of Raman tensor elements was enhanced for the two strongest phonon modes in the low-frequency range, while the anisotropy of the sharpest Raman phonon modes in the high-frequency region decreased. Our comprehensive study has provided meaningful results for comprehending the long-range orderliness and anisotropy in technologically important β-(AlxGa1−x)2O3 crystals.

Ever since the ground-breaking isolation of graphene, numerous two-dimensional (2D) materials have emerged with 2D metal dihalides gaining significant attention due to their intriguing electrical and magnetic properties. In this study, we introduce an innovative approach via anhydrous solvent-induced recrystallization of bulk powders to obtain crystals of metal dihalides (MX 2 , with M = Cu, Ni, Co and X = Br, Cl, I), which can be exfoliated to 2D flakes. We demonstrate the effectiveness of our method using CuBr 2 as an example, which forms large layered crystals. We investigate the structural properties of both the bulk and 2D CuBr 2 using X-ray diffraction, along with Raman scattering and optical spectroscopy, revealing its quasi-1D chain structure, which translates to distinct emission and scattering characteristics. Furthermore, microultraviolet photoemission spectroscopy and electronic transport reveal the electronic properties of CuBr 2 flakes, including their valence band structure. We extend our methodology to other metal halides and assess the stability of the metal halide flakes in controlled environments. We show that optical contrast can be used to characterize the flake thicknesses for these materials. Our findings demonstrate the versatility and potential applications of the proposed methodology for preparing and studying 2D metal halide flakes.

[Display omitted] • Raman scattering spectroscopy and AAS were used to detect heavy metals in fish. • The intensities and area of the peaks increase as heavy metal concentrations increase. • The best modeling of the data was obtained using the Elovich model. • Despite the sensitivity of AAS, its drawbacks are imperative for an alternative technique. • Raman spectroscopy-based approach is rapid, low-cost, and simple to implement. Heavy metals have been widely applied in industry, agriculture, and other fields because of their outstanding physics and chemistry properties. They are non-degradable even at low concentrations, causing irreversible harm to the human and other organisms. Therefore, it is of great significance to develop high accuracy and sensitivity as well as stable techniques for their detection. Raman scattering spectroscopy and atomic absorption spectrophotometer (AAS) were used parallelly to detect heavy metal ions such as Hg, Cd, and Pb of different concentrations in fish samples. The concentration of the heavy metals is varied from 5 ppb to 5 ppm. Despite the satisfactory recoveries of AAS, their drawbacks are imperative for an alternative technique. In Raman scattering spectroscopy, the intensities and areas of the characteristic peaks are increased with increasing the concentration of the heavy metals. For Hg concentration ≥ 1 ppm, a slight shift is observed in the peak position. The obtained values of peak intensity and peak area are modeled according to Elvoich, Pseudo-first order, Pseudo-second order, and asymptotic1 exponential model. The best modeling was obtained using the Elovich model followed by the asymptotic1 exponential model. The introduced Raman spectroscopy-based approach for on-site detection of trace heavy metal pollution in fish samples is rapid, low-cost, and simple to implement, increasing its visibility in food safety and industrial applications. [ABSTRACT FROM AUTHOR]

The class of carbonaceous chondrite meteorites has carbon in their structures, similarly to the terrestrial calcite and dolomite rocks, and contains the group =CO3 linked to Ca and/or Mg, which may be, in principle, more susceptible to the action of the spatial gamma radiation (γ–R) due to the presence of these light-atom elements. On the present work, we used a variety of optical techniques to investigate the possible effects of γ–R produced by an artificial 192Ir source in terrestrial calcite and dolomite, which may allow to understand the effect of the spatial radiation in that celestial bodies of the solar system. As a result, we verified that the γ–R irradiation caused the effect of untrapping of electrons from deep color centers, that spatially migrate to other color centers on the samples, resulting on the change of the electron energetic configuration. [ABSTRACT FROM AUTHOR]

Nanometer‐size graphene sheets (nanographene) were synthesized by the in‐liquid plasma method employing a mixture of alcohols. Pure methanol in‐liquid plasma was found to not synthesize any nanographene. Pure ethanol synthesized nanographene with high crystallinity. Highly crystalline nanographene with a narrow full width‐half maximum of the Raman scattering G‐band (FWHMG) was obtained by mixing 1‐butanol with methanol. This is due to the formation of carbon ring structures being inhibited by the addition of methanol. The ratio of added methanol determined the nanographene crystallinity and yield under a trade‐off relationship, allowing the crystallinity and nanographene yield to be controlled by controlling the ratio. Gas chromatography‐mass spectrometric analysis of by‐products in the liquids' supernatant showed that the crystallinity of the synthesized nanographene correlated with the ratio of carbon over oxygen of the alcohol precursors (C/O), i. e., the amount of hydroxyl groups in the liquids, and hence controlling the C/O ratio can be used to control the graphene crystallinity in the in‐liquid plasma synthesis. [ABSTRACT FROM AUTHOR]

The particulars of the effect of focused femtosecond laser pulses on antimony silicate glass with the composition 25Sb2O3∙75SiO2 % (molar content) in thermal and athermal regimes were studied. It was found that in contrast to quartz, alkali silicate, and some borosilicate glasses the birefringence of the form characteristic for the formation of nanogratings does not arise in the laser-modified zones of the studied glass. Weak birefringence with slow axis parallel to the polarization plane of the writing laser beam, accompanied by precipitation of crystalline phases, seemingly including the cubic modification of Sb2O3, arises in the modified zones under irradiation by 106 pulses with energy > 100 nJ and repetition frequency 10 and 200 kHz. [ABSTRACT FROM AUTHOR]

Deep-ultraviolet continuous-wave photoluminescence spectroscopy is performed for nano-polycrystalline diamond (NPD) synthesized by a high pressure high-temperature technique. NPD exhibits clear deep-ultraviolet emissions, which originate from intrinsic excitonic transitions assisted by a momentum-conserving phonon with a photon. Surprisingly, the peak emission energy is about 30 meV higher than that of the single-crystalline diamond. Raman scattering spectroscopy indicates that the energy difference should originate from the excitonic properties of the NPD and not the phonon. Hence, NPD has a large bandgap compared to single-crystalline diamond. [ABSTRACT FROM AUTHOR]

• Hydrogen incorporation distorts the lattice and changes the electronic structure. • Annealing in H 2 accelerates the ordered L1 0 FePd phase formation compared to vacuum. • Reversible changes in the magnetic states under hydrogen annealing. • Surface-enhanced Raman spectroscopy (SERS) used to study the dynamics of ordering processes in FePd films. • The use of FePd films as templates increases the sensitivity of the SERS method. The effect of the annealing environment (vacuum, hydrogen) in the temperature range of 400 °C − 700 °C on the thermally activated ordering processes in the equiatomic FePd films is investigated. The absorption of hydrogen atoms affects the electronic structure and, therefore, the magnetic properties of the film. Ordering processes occur much faster under interaction with hydrogen than during annealing in a vacuum. It is shown that by changing the annealing parameters of the FePd film in a hydrogen atmosphere, it is possible to control the phase composition, reversibility of magnetic states: ferromagnetic ↔ paramagnetic. The application of the Raman spectroscopy allows identifying the dynamics of structural changes in the FePd films during the study of ordering processes. [ABSTRACT FROM AUTHOR]

Densified Ba1−xLaxSnO3 (BLSO) ceramics were synthesized at relatively lower sintering temperature by a conventional solid state reaction route. X-ray diffraction (XRD) analysis using the Reitveld refinement technique inferred cubic (space group Pm–3m) average crystalline structure. The effect of La-substitution on variations of lattice parameters could be attributed to two competing factors, viz. ionic radii of the dopant and partial reduction of Sn4+ into Sn2+. XRD data indicate local symmetry reduction from cubic to orthorhombic (Pbnm), evident from the observed splitting in {211}p and {310}p peaks of pseudo cubic structure, as well as corresponding super reflections. The synthesized ceramics were highly porous with percentage densification in the range (60–70)% due to the relatively low sintering temperature used. Densification was improved using 2 wt.% Bi2O3 as a sintering aid, which resulted in highly dense ceramics with relative density ≈ 95%. Sintering temperature reduction of ≈ 300°C was also achieved relative to that required in normal solid state synthesis. This is very important to reduce defects and inhibit uneven grain growth. Microstructure and elemental analysis probed through scanning electron microscopy and energy-dispersive x-ray spectroscopy revealed that Bi replaces lanthanum and that liquid phase sintering is mainly responsible for the high densification using the sintering aid. The structural indicators of symmetry reduction were corroborated by experimentally observed Raman modes in an otherwise symmetry-forbidden cubic phase. The local symmetry reduction is attributed mainly to octahedral tilts corresponding to orthorhombic symmetry. [ABSTRACT FROM AUTHOR]

Abstract Special pure 1300 ppmw Pr(3+)-doped Ga 3 Ge 31 As 18 Se 48 glass is prepared; its microstructure, impurity content, thermal, crystallization, optical and photo-luminescent properties are investigated. The glass microstructure, according to Raman scattering spectroscopy data, consists mainly of Ge(Se 1/2) 4 , As 4 Se 3 and (Se 3/2)Ge–Ge(Se 3/2) structural units. The glass has a low content of residual impurities, a wide transmission range (0.9–16 µm), a high glass transition temperature (356 °C), and a low tendency to crystallization. When pumping laser radiation at a wavelength of 1.56 µm, the studied glass shows intense photoluminescence in the spectral regions 2.1–3.2 µm and 3.5–6 µm. The measured emission lifetime at 4.5–5 µm wavelengths was 12.5 ms. The obtained Pr(3+)-doped chalcogenide glass is promising for fabrication of active mid-IR optical fibers. [ABSTRACT FROM AUTHOR]

Abstract Experimental and theoretical investigations are reported to comprehend the structural and lattice dynamical properties of high quality Bridgman grown zb Zn 1 -x Mn x Te (x ≤ 0.15) crystals. Our detailed far-infrared reflectivity and Raman scattering measurements ascertained atypical "intermediate-phonon-mode" behavior for the alloys. Besides perceiving ZnTe- and zb MnTe-like LO and TO phonons, a weak Mn alloy-disorder mode near ∼205 cm−1 is observed. A classical "Drude-Lorentz" model is used for evaluating the dielectric tensors of ternary alloys to simulate composition dependent reflectivity spectra – providing results in good agreement with the experimental data at near normal incidence. Lattice relaxation effects around Mn Zn and Zn Mn from the synchrotron radiation extended x-ray absorption experiments are meticulously incorporated to help construct the perturbation models for simulating impurity modes using a realistic rigid-ion-model in the frame work of an average t -matrix Greens function theory – reconfirming on much firmer ground – the observed intermediate phonon mode behavior. Graphical abstract Image 1 Highlights •Structural and lattice dynamical properties are reported on high quality Bridgman grown Zn 1-x Mn x Te (ZMT) alloys (x ≤ 0.15). •Atypical "intermediate-phonon mode" behavior is assessed by Raman scattering and infrared reflectance spectroscopies. •Local inter-atomic structures are estimated by synchrotron radiation x -ray absorption fine structure (SR-EXAFS) measurements. •Classical Drude-Lorentz model is applied to explicate far infrared reflectance features in ZMT alloys. •Lattice relaxation effects of Mn Zn and Zn Mn are incorporated to simulate impurity modes – reconfirming intermediate phonon mode behavior of ZMT alloys. [ABSTRACT FROM AUTHOR]

Nanoporous glass is a universal matrix in which impregnation with different substances can trigger the appearance of properties which are uncharacteristic for glass. Heat treatment, creating material with a specified structure and properties, can be used to control the porosity of the glass. In the present work the effect of heat treatment on the structure of gold-impregnated porous glass was studied and it became apparent that this material has potential as an active substrate for Raman scattering spectroscopy. [ABSTRACT FROM AUTHOR]

Flexural elastic deformations of single-crystal silicon have been studied using microspectral Raman scattering. Results are reported on nano-scaled sign-changing shifts of the main peak of the microspectral Raman scattering within the single-crystal silicon cantilever beam during exposure to flexural stress. The maximum value of Raman shift characteristic of the 518 cm−1 silicon peak at which elasticity still remains has been found to be 8 cm−1 which corresponds to an applied deformation of 4 GPa. We report three-dimensional maps of the distribution of internal stresses at different levels of deformation up to irreversible changes and brittle fracture of the samples that clearly show compression and tension areas and an undeformed area. A qualitative explanation of the increase in the strength of the cantilever beam due to its small thickness (2 μm) has been provided that agrees with the predictions of real-world physical parameters obtained in SolidWorks software environment with the SimulationXpress module. We have defined the relative strain of the beam surface which was 2% and received a confirmation of changes in the silicon lattice parameter from 0.54307 nm to 0.53195 nm by the BFGS algorithm.

Abstract We studied X-ray irradiation effects of the single-walled carbon nanotubes (SWNTs) encapsulating ferrocene (Cp 2 Fe) molecules. Cp 2 Fe was encapsulated into SWNT by thermal treatment at 200 °C for 12 h in a vacuum-sealed glass tube. Raman scattering spectroscopy revealed that the SWNT after the encapsulation showed a high-frequency shift of the radial breathing modes (RBMs). The similar high-frequency shift was reported for the Cp 2 Fe encapsulated SWNT, and therefore we concluded that the Cp 2 Fe molecules were successfully encapsulated in SWNT. The exposure of the encapsulated SWNT with 1.25 keV X-ray gave the enhancement of the defect-related band, D band, but not shift the RBM peak in the Raman scattering spectra. The energy dispersive X-ray spectroscopy revealed that the X-ray irradiation reduced the atomic concentration of Fe from 0.24% to 0.15%. The result suggests that the X-ray irradiation leads to the emission of Cp 2 Fe molecules. [ABSTRACT FROM AUTHOR]

Local crystallization of barium titanate silicate glass under the action of femtosecond laser beam was studied. The effect of the scan rate of the laser beam and the energy of the laser pulses on the morphology of the channels containing crystals of fresnoite Ba2TiSi2O8 was determined. Polarization Raman scattering spectroscopy was used to determine the predominant orientation of fresnoite crystals with formed channels. The results open up prospects for developing and fabricating waveguide crystal structures with low optical losses for photonics and integrated optics. [ABSTRACT FROM AUTHOR]

The authors have deposited the diamond-like carbon (DLC) films by radio frequency inductively coupled plasma enhanced chemical vapor deposition (RF ICP PECVD) method. The investigated DLC films with different sp3 fraction content were deposited on polished and textured silicon substrates. The sp3 fraction content of the deposited DLC films was ranging from 35 % to 70 % and was estimated from acquired Raman scattering spectra (excitation wavelength: 325 nm and 514.5 nm). The measurements of field emission characteristics were carried out in diode configuration. Emission properties of the DLC films were calculated from Fowler-Nordheim plots. The calculated electric field enhancement factor β was ranging from 56 to 198 for the DLC films deposited on polished substrates and from 115 to 445 for films deposited on textured substrates. The surface of the DLC films was observed by scanning electron microscope (SEM) after field emission measurements. The acquired SEM images reveled that the activation of field emission from the DLC films is connected with generation of structural damage to the DLC films. [ABSTRACT FROM AUTHOR]

Comprehensive experimental and theoretical studies are reported to assess the vibrational and structural properties of 3C-SiC/Si (001) epilayers grown by chemical vapor deposition in a vertical reactor configuration. While the phonon features are evaluated using high resolution infrared reflectance (IRR) and Raman scattering spectroscopy (RSS) – the local inter-atomic structure is appraised by synchrotron radiation extended x-ray absorption fine structure (SR-EXAFS) method. Unlike others, our RSS results in the near backscattering geometry revealed markedly indistinctive longitudinal- and transverse-optical phonons in 3C-SiC epifilms of thickness d < 0.4 μm. The estimated average value of biaxial stress is found to be an order of magnitude smaller while the strains are two-orders of magnitude lower than the lattice misfits between 3C-SiC and Si bulk crystals. Bruggeman’s effective medium theory is utilized to explain the observed atypical IRR spectra in 3C-SiC/Si (001) epifilms. High density intrinsic defects present in films and/or epilayer/substrate interface are likely to be responsible for ( a ) releasing misfit stress/strains, ( b ) triggering atypical features in IRR spectra, and ( c ) affecting observed local structural traits in SR-EXAFS. [ABSTRACT FROM AUTHOR]

Diborides of group IV transition metals are considered in the context of the features of two types of adsorption (physical and chemical) during interaction of polycrystalline and nanocrystal materials (carbon nanotubes, highly dispersed iron powder etc.) with gases (CO2, H2O-vapor). Due to Raman scattering spectroscopy, it is established that, in the case of adsorption, only gas chemical adsorption with typical minimal distance between absorbed gas molecule and adsorbing agent surface occurs on the surfaces of all synthesized nanoparticles. It is confirmed that the reference Raman spectrum of the correspondent nanoparticles (according to the Hirsch reference book) remains in all cases. The adsorption of oxygen and nitrogen during oxidation of diborides of group IV transition metals is investigated. [ABSTRACT FROM AUTHOR]

Raman scattering (RS), Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopic measurements on β -MnO 2 and α -K x MnO 2 nanorods were performed. The infrared spectrum of β -MnO 2 is sensitive towards the particle sizes, while the Raman spectrum is sensitive towards the presence of nonstoichiometric and disordered MnO 2- δ on the surface of nanorods. EPR measurements show the appearance of two types of Mn 4+ ions having different local environment: (i) Mn 4+ ions in Mn 4+ -rich environment and (ii) Mn 4+ ions in mixed-valence Mn 4+ /Mn 3+ environment that match up with region of nonstoichiometric MnO 2- δ . Observed bands in vibrational spectra of tetragonal hollandite-type α -K x MnO 2 are considered to be mainly due to the vibration modes of Mn O frameworks. The EPR spectra of α -K x MnO 2 nanorods contain two signals that can be attributed to Mn 4+ ions in Mn 4+ -rich environment and Mn 4+ ions in mixed-valence Mn 4+ /Mn 3+ environment close to K + ions. [ABSTRACT FROM AUTHOR]

Spectral microscopy provides information about the spatial distribution and physiological functional states of pigment-protein complexes in photosynthetic organisms. This can be used to complement the newly developed techniques, such as cryogenic electron microscopy and atomic force microscopy, which are less effective in functional analysis of photosynthesis, despite having an excellent spatial resolution. The combination of optical microscopies with various spectroscopic techniques has extended the possibility of a multi-perspective investigation in photosynthesis research. Some of these spectroscopic techniques include fluorescence and absorption spectra, excitation spectra, time-resolved fluorescence measurement, Raman scattering spectroscopy, etc. These techniques can be applied to in vivo investigations of photosynthetic activity without introducing any artificial fluorophore since the photosynthetic pigments are informative probes. In particular, the technique has been effective in clarifying the dynamic physiological responses of photosynthetic organisms to variable environments. In this paper, we review the recent progress in spectral microscopy in the field of in vivo photosynthesis research. We have also introduced and discussed some distinctive spectral microscopies such as anti-Stokes fluorescence spectral microscopy, excitation spectral microscopy, cryo-microscopy, and Raman spectral microscopy. • Review and perspective of spectroscopic microscopy in photosynthetic studies. • Fluorescence spectra and excitation spectra are powerful for the multi-pigment system. • Fluorescence lifetime imaging senses dynamics of electronic excitation at microscale. • Absorption and Raman spectral microscopy to quantify nonfluorescent molecules. • Cryo-spectral microscope to observe arrested states during physiological changes. [ABSTRACT FROM AUTHOR]

Vertical graphene nanosheets (VGN) were prepared by a microwave plasma-enhanced chemical vapor deposition technique on glass and fused silica. Their quality was explored by Raman scattering spectroscopy and transient absorption spectroscopy (TAS). We have observed a correlation between Raman scattering spectroscopy data and TAS parameters (charge carrier relaxation times and relative transient absorption signal amplitude). The substrate-related effects were explained by competition between the changes in the size of the effects induced by the graphene nanocrystallite, the substrate-induced graphene self-doping, and the presence of on-site and vacancy defects along with the dominant boundary defects. The optical and electrical properties of VGN on glass deposited at low substrate temperature (600 °C) were similar or even better compared to VGN on fused silica. The ability to prepare high-quality VGN on glass could be very attractive for practical application due to the low substrate price. [ABSTRACT FROM AUTHOR]

We report the results of experimental studies on cardiac implants using a Raman spectroscopy method (RS). Raman spectra characteristics of leaves and walls of cardiac implants were obtained; the implants were manufactured by protocols of detergent-enzymatic technique (DET) and biological, detergent-free (BIO) decellularization, using detergents (group DET) or a detergent-free, nonproteolytic, actin-disassembling regimen (BIO). There were input optical coefficients that allowed us to carry out evaluation of the protocols of DET and BIO decellularization on the basis of the concentrations of glycosaminoglycans, proteins, amides, and DNA. It was shown that during DET and BIO decellularization, composition aberrations of proteins and lipids do not occur and the integrity of the collagenous structures is preserved. It was found that during the DET decellularization, preservation of glycosaminoglycans is better than during BIO decellularization. [ABSTRACT FROM AUTHOR]

The samples of GeS 1.35 glasses were synthesized with germanium and sulfur of natural isotopic composition and with isotopically enriched germanium ( 72 Ge, 74 Ge, 76 Ge). The glasses were investigated by the method of Raman scattering spectroscopy (RSS). It was shown that GeS 4/2 tetrahedrons and structural units containing Ge Ge homobonds are present in glasses. The quantum-mechanical calculation of the frequency of fundamental vibrational modes in glass network was carried out. Their dependencies on the atomic mass of germanium were used for identification of bands in RS (Raman scattering) spectra. [ABSTRACT FROM AUTHOR]

Sulfur is extensively used to increase the bandgap of Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells and to improve the open circuit voltage ( VOC) in order to optimize the characteristics of the devices. This study uses a sulfurization process to obtain a double-graded bandgap profile. Selenization was carried out on Cu(In,Ga) precursors, followed by one sulfurization process or two consecutive sulfurization processes on top of the CIGSe absorber layer surface. The optimum two-step sulfurization process provides an increase of VOC of 0.05 V and an improvement of conversion efficiency of 1.17%. The efficiency of the 30 × 30 cm2 monolithic module, which has 64 CIGS cells connected in series (aperture area: 878.6 cm2), is 15.85%. The optical and electrical properties of the phase and the work function distribution were investigated using the depth profiles of the absorber layer as a function of the sulfurization conditions. The CIGSSe thin film formed by two-step sulfurization with a high sulfur concentration exhibits a single work function peak, better crystallinity, and higher conversion efficiency than those of the thin film formed by two-step sulfurization at low sulfur concentration. In terms of the Raman spectra depth profile, the phase areas for the CIGSSe thin film that underwent the optimized high sulfur concentration two-step-sulfurization appeared to have less of Cu2-xSe phase than that with low sulfur concentration. Consequently, surface and interface phase analysis is an essential consideration to improve cell efficiency. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nowadays electronic industries prerequisites magnetic materials, i.e., iron rich materials and their magnetic alloys. However, with the advent of high frequency applications, the standard techniques of reducing eddy current losses, using iron cores, were no longer efficient or cost effective. Current market trends of the switched mode power supplies industries required even low energy losses in power conversion with maintenance of adequate initial permeability. From the above point of view, in the present study we aimed at the production of Manganese–Zinc ferrites prepared via solution combustion method using mixture of fuels and achieved low loss, high saturation magnetization, high permeability, and high magnetic domain relaxation frequency. The as-synthesized Zn 2+ substituted MnFe 2 O 4 were characterized by X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The fractions of Mn 2+ , Zn 2+ and Fe 2+ cations occupying tetrahedral sites along with Fe occupying octahedral sites within the unit cell of all ferrite samples were estimated by Raman scattering spectroscopy. The magnetic domain relaxation was investigated by inductance spectroscopy (IS) and the observed magnetic domain relaxation frequency ( f r ) was increased with the increase in grain size. The real and imaginary part of permeability ( μ ′ and μ ″) increased with frequency and showed a maximum above 100 MHz. This can be explained on the basis of spin rotation and domain wall motion. The saturation magnetization ( M s ), remnant magnetization ( M r ) and magneton number ( µ B ) decreased gradually with increasing Zn 2+ concentration. The decrease in the saturation magnetization was discussed with Yafet–Kittel (Y–K) model. The Zn 2+ concentration increases the relative number of ferric ions on the A sites, reduces the A–B interactions. The frequency dependent total power losses decreased as the zinc concentration increased. At 1 MHz, the total power loss ( P t ) changed from 358 mW/cm 3 for x =0–165 mW/cm 3 for x =0.9. P t for all the Zn doped samples exhibited the temperature stability up to 100 °C. [ABSTRACT FROM AUTHOR]