Band Shape Research Articles

ELECTRON IRRADIATED PI2610 POLYIMIDE FILMS ON MONOCRYSTALLINE SILICON

The optical and strength properties of electron-irradiated films of a polyimide composition (polyimide PI2610) deposited on the surface of single-crystalline silicon wafers of the KDB-10 grade by centrifugation were studied. Irradiation with electrons with an energy of 5 MeV was carried out on a linear accelerator U-003 in the dose range 1·1014 – 2·1015 cm–2. It has been experimentally established that at an irradiation dose of Ф = 1∙1014 cm–2, relaxation of elastic stress fields in the polyimide film is observed, which is expressed in modification of the shape of bands with maxima at 1349 and 1700 cm–1, caused by vibrations of the C–N–Cst bond and the C=O double bond imide ring. Polyimide PI-2610 films on silicon are quite stable when irradiated with electrons. A noticeable transformation of the ATR spectrum at a dose of 2∙1015 cm–2 was observed only in the region of stretching vibrations of C–H and O–H bonds, which is due to radiation-induced processes on by-products of polyimide synthesis and residual solvents. No noticeable decrease in the intensity of absorption bands caused by vibrations of the skeleton of the aromatic ring, imide ring, single and double C–C and C–O bonds, and imide C=O bonds was observed.

Assessing the accuracy of TD-DFT excited-state geometries through optimal tuning with GW energy levels.

We study the accuracy of excited state (ES) geometries using optimally tuned LC-PBE functionals with tuning based on GW quasiparticle energies. We compare the results obtained with the PBE, PBE0, non-tuned, and tuned LC-PBE functionals with available high-level CC reference values as well as experimental data. First, we compare ES geometrical parameters obtained for three different types of systems: molecules composed of a few atoms, 4-(dimethylamino)benzonitrile (DMABN), and conjugated dyes. To this end, we used wave-function results as benchmarks. Next, we evaluate the accuracy of the theoretically simulated spectra as compared to the experimental ones for five large dyes. Our results show that, besides small compact molecules for which tuning LC-PBE does not allow obtaining geometries more accurate than those computed with standard functionals, tuned range-separated functionals are clearly to be favored, not only for ES geometries but also for 0-0 energies, band shapes, and intensities for absorption and emission spectra. In particular, the results indicate that GW-tuned LC-PBE functionals provide improved matching with experimental spectra as compared to conventionally tuned functionals. It is an open question whether TD-DFT with GW-tuned functionals can qualitatively mimic the actual many-body Bethe-Salpeter (BSE/GW) formalism for which analytic ionic gradients remain to be developed.

Plastic Optical Fiber Spectral Filter Based on In-Line Holes

We propose a spectral filter based on a plastic optical fiber with micro-holes as a low-cost, robust, and highly reproducible spectral filter. The spectral filter is explored for two configurations: a fiber extended in a straight line and a fiber optic loop mirror scheme configuration. The transmission traces indicate a spectral blue shift in peak transmission, at 587 nm, 567 nm, 556 nm, and 536 nm for zero, one, two, and three holes in the fiber, respectively. The filter exhibits a bandpass period of approximately 120 nm. Additionally, we conduct a comparison of the transmission with holes separated by distances of 1 cm and 500 μm. The results demonstrate that the distance between holes does not alter the spectral transmission of the filter. In the case of the fiber loop mirror configuration, we observe that the bandpass can be adjusted, suggesting the presence of multimode interference. Exploring variations in the refractive index within the holes by filling them with glucose solutions at various concentrations, we determine that the filtering band and spectral shape remain unaltered, ensuring the stable and robust operation of our spectral filter.

Possible influence of Martian surface mineralogy on the detectability of atmospheric trace gases - mid-infrared simulation results

The paper focuses on the influence of the optical properties of Martian surface minerals on remotely detected gaseous components of the Martian atmosphere, when the spectrometer receives a combined signal from the Martian soil and atmosphere. Our considerations are primarily concerned with the detectability of methane, but the problem may also apply to other trace gases. Detections of methane in the Martian atmosphere have been reported from Mars Express (orbiting Mars), the Curiosity rover on the Martian surface, and from Earth. Its presence in the Martian atmosphere is being questioned today. The reason for these doubts is that both spectrometers onboard ExoMars Trace Gas Orbiter have not yet detected any methane in the Martian atmosphere using the very sensitive solar occultation method. The solar occultation method is unable to probe the lowest layers of the atmosphere at mid-latitudes, and so, its presence in this part of the atmosphere is assumed to be due to its possible source in the ground, as suggested by some works.This paper considers whether the spectral characteristics of the soil may hinder the remote detection of methane. One of the examples discussed in the article relates to the possible observation of methane over mineralogical surfaces that may be the source of this gas. The examples of other surface mineralogical compositions are also discussed. The series of numerical simulations carried out in the region of the strong methane absorption band and the examples where the optical properties of the surface change the shape and contrast of this absorption band are shown. The codes used provide estimates of the spectral reflectance/emittance and total radiance of the Martian surface and atmosphere in the mid-infrared spectral region. The surface covered by dust was described by the reflectance and emittance calculated from n,k using Mie and Hapke theories or known from laboratory measurements. The different concentrations of atmospheric trace gases were taken into account.

Numerical analysis of thermal and mechanical characteristics with property maps in complex semiconductor package designs

As semiconductor performance improves through advanced package designs, it becomes important to consider both thermal and mechanical properties. Better understanding their relationship enhances system design and optimization. This study has introduced a numerical method that takes into account both thermal and mechanical fluxes to construct thermal and mechanical property maps for practical application in semiconductor engineering. Furthermore, this paper investigated the relationship between the two properties using the constructed property maps in commercially available semiconductor packages. Owing to the complexity of packaging design patterns, a coupled isoparametric mapping and machine learning (ML) method was introduced to investigate their effects. The model then determines and investigates the anisotropic equivalent thermal and mechanical properties of the commercialized semiconductor packages with complex pattern designs, according to the package materials, volume fractions of each material, and design patterns. This approach pursues more sophistication and practicality compared to simplified composite structure property evaluation models. Additionally, all processes in the algorithm are automated based on ML methods, making them practically applicable in the semiconductor industry. The study shows that there is a strong correlation between the thermal and mechanical characteristics in the complex package patterns. This relationship was able to form a fairly clear category based on the shape of the dielectric band because the dielectric band had significantly different effects on the thermal and mechanical fluxes. The study discussed the physical implications of the similarities and differences between the two behaviors and validated the results of the equivalent properties through finite element (FE) analysis. Finally, the study cross-validates the relationship by showing that information from one flux behavior can be used to predict the other based on the ML method. Based on the results, this paper can provide a better understanding of thermal and mechanical fluxes in semiconductor package patterns for package design and optimization.

Distinguishing IDH mutation status in gliomas using FTIR-ATR spectra of peripheral blood plasma indicating clear traces of protein amyloid aggregation

BackgroundGlioma is a primary brain tumor and the assessment of its molecular profile in a minimally invasive manner is important in determining treatment strategies. Among the molecular abnormalities of gliomas, mutations in the isocitrate dehydrogenase (IDH) gene are strong predictors of treatment sensitivity and prognosis. In this study, we attempted to non-invasively diagnose glioma development and the presence of IDH mutations using multivariate analysis of the plasma mid-infrared absorption spectra for a comprehensive and sensitive view of changes in blood components associated with the disease and genetic mutations. These component changes are discussed in terms of absorption wavenumbers that contribute to differentiation.MethodsPlasma samples were collected at our institutes from 84 patients with glioma (13 oligodendrogliomas, 17 IDH-mutant astrocytoma, 7 IDH wild-type diffuse glioma, and 47 glioblastomas) before treatment initiation and 72 healthy participants. FTIR-ATR spectra were obtained for each plasma sample, and PLS discriminant analysis was performed using the absorbance of each wavenumber in the fingerprint region of biomolecules as the explanatory variable. This data was used to distinguish patients with glioma from healthy participants and diagnose the presence of IDH mutations.ResultsThe derived classification algorithm distinguished the patients with glioma from healthy participants with 83% accuracy (area under the curve (AUC) in receiver operating characteristic (ROC) = 0.908) and diagnosed the presence of IDH mutation with 75% accuracy (AUC = 0.752 in ROC) in cross-validation using 30% of the total test data. The characteristic changes in the absorption spectra suggest an increase in the ratio of β-sheet structures in the conformational composition of blood proteins of patients with glioma. Furthermore, these changes were more pronounced in patients with IDH-mutant gliomas.ConclusionsThe plasma infrared absorption spectra could be used to diagnose gliomas and the presence of IDH mutations in gliomas with a high degree of accuracy. The spectral shape of the protein absorption band showed that the ratio of β-sheet structures in blood proteins was significantly higher in patients with glioma than in healthy participants, and protein aggregation was a distinct feature in patients with glioma with IDH mutations.

Tailoring structural, electronic, elastic and optical properties of Strontium-based XSrO3 (X = Rb, Cs) oxide perovskites employing density functional theory

The structural, electrical, optical, and elastic characteristics of Strontium-based oxide perovskites, specifically RbSrO3 and CsSrO3, have been meticulously examined using the Wien2k package inside the density functional theory (DFT) framework. Our structural analysis has confirmed the stability of these compounds, indicating that they adopt a cubic crystal structure belonging to the pm-3m (#221) space group. Moving on to their electrical characteristics, band shape, and state density have been calculated, which collectively point to the metallic characteristics of both RbSrO3 and CsSrO3. Additionally, delving into the elastic properties of these materials, considering elastic constants, bulk modulus, anisotropy factor, Poisson’s ratio, Pugh’s ratio. Pugh’s ratio, in particular, sheds light on the ductile character of these optoelectronic compounds, while the ionic character is resolved through the evaluation of the Cauchy pressure. Furthermore, the optical properties have been investigated, covering several factors, including the refractive index, dielectric function, absorption coefficient, reflectivity, and optical conductivity within an energy range spanning from 0 eV to 15 eV. Our comprehensive analysis of these compounds reveals their potential as promising candidates for optoelectronic devices, showcasing their diverse and favorable properties in this regard.

VCD spectra of chiral naphthalene-1-carboxamides in the solid-state

The VCD spectra of chiral 2,3-dihydro-1H-benzo[de]isoquinolin-1-one (8-substituted naphthalene-1-carboxamide, BIQ) were studied in KBr pellets. The X-ray diffractometry revealed that the Me, Ph, and pClPh BIQs crystalize in the monoclinic P21, while nBu, pMePh, and oMeOPh BIQs in the orthorhombic P212121 space group. Only the Me-BIQ crystal exhibits the presence of cyclic amide dimers, while the others contain chains of the amid group hydrogen bonds. For all BIQs, except pMePh, the most intense IR band in the 1750–1550 cm−1 region is located at ca. 1680 cm−1 and is accompanied by two weak ones at ca. 1618 and 1590 cm−1. For the pMePh derivative, four almost equally intense IR bands at 1662, 1639, 1614, and 1588 cm−1 are observed. This region of the IR spectra of BIQs, but pMePh, is well reproduced by calculations based on BIQ monomers. On the other hand, the complex IR pattern of pMePh is computationally reproduced when larger crystal fragments, like octamers, are considered. Registration of the VCD spectra enabled recognizing the complexity of IR contours at ca. 1680 cm−1 by the corresponding VCD motives. For (i) Me, Ph and pClPh (R)-enantiomers, two (+)(–) bands were distinguished and for (ii) nBu and pMePh ones, one VCD band with right-side asymmetry was found. For (iii) oMeOPh the VCD pattern cannot be unambiguously assigned. Thus, the VCD spectra in the ν(C=O) range diverse the studied compounds. Among the set of molecules, pMePh has exceptional crystal geometry. Therefore, its most intense ν(C=O) band position and shape can be connected with the geometry of the hydrogen bonds, interactions, and crystal packing. Interpretation of the VCD spectra is based on linear and packed BIQ octamers. This cluster model can reproduce the main features of the solid-state VCD of BIQs.

Analytical method for stable background reduction for Raman spectra of carbon‐containing meteorite and terrestrial samples suffering from intense fluorescence

AbstractChemical states of carbon in terrestrial (meta) sediments and carbonaceous chondrites gather attention as a geothermometer. As a nondestructive analytical method, Raman spectroscopy has been widely used to study their electronic properties, crystallinity, and structural defects through so‐called D and G bands. For the analysis of Raman spectra, a common problem is coexistence of a fluorescence background, which should be subtracted prior to the peak‐fitting analysis. However, we recently faced a problem that the band shape noticeably changed depending on the background function assumed although the background seemed to be well subtracted at a first glance regardless of the choice of the background function. For the application of the Raman spectroscopy as a geothermometer, a standard background subtraction method must be established to suppress the arbitrariness. In the present study, Raman spectra of seven carbon‐containing natural samples, whose background intensities were significantly different, were measured, and their background shape was evaluated by first‐, second‐, and third‐order polynomials. The results indicated that the third‐order polynomial was necessary and sufficient as a standard background function. Importantly, although lower order polynomials seem to successfully fit the background at a first glance, they falsely caused dispersion of the shoulder band shape.

One- and two-photon absorption spectra of organoboron complexes: vibronic and environmental effects.

We synthesized a series of four parent aza-β-ketoiminate organoboron complexes and performed spectroscopic studies using both experimental and computational techniques. We studied how benzannulation influences the vibronic structure of the UV/Vis absorption bands with a focus on the bright lowest-energy π → π* electronic excitation. Theoretical simulations, accounting for inhomogeneous broadening effects using different embedding schemes, allowed gaining in-depth insights into the observed differences in band shapes induced by structural modifications. We observed huge variations in the distributions of vibronic transitions depending on the position of benzannulation. By and large, the harmonic approximation combined with the adiabatic hessian model delivers qualitatively correct band shapes for the one-photon absorption spectra, except in one case. We also assessed the importance of non-Condon effects (accounted for by the linear term in Herzberg-Teller expansion of the dipole moment) for S0 → S1 band shapes. It turned out that non-Condon contributions have no effect on the band shape in one-photon absorption spectra. In contrast, these effects significantly change the Franck-Condon band shapes of the two-photon absorption spectra. For one of the studied organoboron complexes we also performed a preliminary exploration of mechanical anharmonicity, resulting in an increase of the intensity of the 0-0 transition, which improves the agreement with the experimental data compared to the harmonic model.

Exceptional thermoelectric performance in AB2Sb2-type Zintl phases through band shaping

We obtained exceptional power factors and zT values in p-type Mg3Sb2-based materials by alloying Zn at the Mg2 sites for double band degeneracy and alloying Yb at the Mg1 sites of Mg3Sb2 for decreased band effective mass.

Luminescence spectrum of cadmium chalcogenide photovoltaic film structures and their power enhancement

A technology has been developed for producing photovoltaic film structures of CdTe, CdTe:In, CdTe/CdS by thermal vacuum deposition, which allows increasing their operating power. An analysis of their low- temperature photoluminescence spectra shows a significant increase in their spectral sensitivity. It has been experimentally shown that there is a clear correlation between the anomalous photovoltaic (APV) properties and the shape of the intrinsic photoluminescence band of obliquely deposited CdTe films. The photoluminescence spectrum of a polycrystalline CdTe film with APV property is qualitatively different from the spectra of a single crystal, large-block polycrystal and single microcrystal. The main contribution to the photoluminescence of the film comes from radiative recombination of free carriers (A-line with half-width ΔEA≈14.2±0.1 meV) and edge luminescence with a wide doublet structure (B- and C - lines with half- widths 18.5±0.1 meV and 32.2±0.1 meV). When doped with In impurities and as a result of heat treatment, the emission spectrum is greatly transformed in accordance with the change in the photoelectric properties of the film. In the photoluminescence spectrum of a CdTe layer in a CdTe/CdS heterostructure grown under identical technological conditions as a CdTe monolayer, an additional broad spectral line appears due to the presence of a heterointerface, the superhot region disappears, and the A-emission line narrows somewhat (ΔEA≈11.2±0.1 meV), which significantly differ the studied film structures from the known CdS/CdTe heterosystems of other authors. The proposed method for analyzing low-temperature photoluminescence spectra makes it possible to purposefully control the technology for manufacturing photovoltaic film structures. The results obtained are of interest for film optoelectronics and solar cell manufacturing.

Experimental and theoretical investigation of the Auger electron spectra of isothiocyanic acid, HNCS.

We investigate isothiocyanic acid, HNCS, by resonant and nonresonant Auger electron spectroscopy at the K-edge of carbon and nitrogen, and the L2,3-edge of sulfur, employing soft X-ray synchrotron radiation. The C1s and N1s ionization energies as well as the S2s and S2p ionization energies are determined and X-ray absorption spectra reveal the transitions from the core to the virtual orbitals. Final states for all normal Auger electron spectra and the resonant ones recorded at the carbon and nitrogen edge are assigned and rationalized with theoretical spectra obtained with a wave-function based protocol. The latter is based on ab initio configuration-interaction representations of the bound part of the electronic wave functions, the one-center approximation for Auger intensities, and a moment theory for band shapes. The computed spectra are in very good agreement with the experimental data and most of the relevant signals are assigned. The double ionization energy is derived from the S2p1/2 spectrum and in good agreement with a recently determined value. The Auger electron spectra are compared with those of the congener HNCO. A similar shape of the normal Auger electron spectra was found for the low binding energy final states, while intensities differed. Similarities are less pronounced in the resonant Auger electron spectra.

Crystallization and luminescence properties of Er/Yb-doped glass-ceramics based on A2O-ZnO-SiO2 system (A = Li, Na, K, Cs)

Er/Yb-doped glass-ceramics from the A2O-ZnO-SiO2 system (A = Li, Na, K, Cs) were prepared. The glass-ceramics contained different crystalline phases, including zinc oxide ZnO, zinc silicate Zn2SiO4 (willemite) or alkali zinc silicates A2ZnSiO4. The tendency to crystallize was shown to increase with decreasing radius of the alkali ions, from Cs+ to Li+. The Na2O-ZnO-SiO2 system was found to be favorable for the crystallization of the rhombohedral modification of Zn2SiO4 (willemite) while the K2O-ZnO-SiO2 system was shown to contain the largest amount of ZnO (zincite). The high crystallinity of the samples caused by annealing the samples to temperatures above 800 °C resulted in a significant increase in the emission intensity around 1.5 µm, a change in the shape of the luminescence band and an increase in the emission lifetime at 1.5 µm from a value cca 10 ms up to a 15 ms.

Monitoring the reduction of UO3 thin film by hydrogen atoms using valence-level spectroscopy: correlating the U5f1 signal to surface hydroxyls

The reaction of a UO3 thin film with atomic hydrogen was studied by He(II) ultraviolet photoelectron spectroscopy (UPS) in the temperature range 190–300 K. UO3 reduction was instantaneously observed once it contacted H atoms at 10–7 torr. The reduction was manifested by the presence of U5f1 electrons in He(II) UPS at approximately 1.5 eV below the Fermi level. Based on the peak characteristics, the valence band shape (composed largely of O2p orbitals in addition to some contribution from U6d and U5f orbitals), and X-ray photoelectron spectroscopy (XPS) U4f lines, the reduction of U6+ in UO3 only results in the formation of U5+ cations and was largely limited to those on the surface. Associated with the reduction was the formation of surface hydroxyls (-OH species) due to the transfer of a proton of the H atom (H.) to surface oxygen ions, while the electron of H. is transferred to a U5f orbital. The pseudo-first-order rate constant of the initial rate of reduction at 10–7 torr and 190 K was found to be approximately 0.01 s–1. Qualitative analysis of the valence band before and after reduction indicates that O2p hybridization with U6d and U5f orbitals leads to well-distinguished features that are characteristic of UO3, U2O5, and UO2. These features, which were quantitatively reversed during the redox process, furthers the assessment of the stoichiometry of a given binary uranium oxide.

Improved Separation in Horizontal Protein SDS-PAGE with Double-Deck Flat Electrodes and a Field Inversion Gel Electrophoresis Module.

The horizontal flatbed electrophoresis method is employed to separate protein samples, providing greater flexibility for various electrophoretic applications and easier sample loading compared to its vertical counterpart. In the currently available equipment setup, cathode and anode electrodes are positioned on top of a gel at each end. Since an electric field enters the gel from the top, its strength gradually weakens from the top to the bottom of the gel. When examining the interior of gels following electrophoretic separation, the uneven electric field causes the protein bands to lie down forward in the direction of migration, leading to an increase in bandwidth. This issue has remained unaddressed for several decades. To address this problem, new clamp-shaped and double-deck electrodes were developed to apply an electric field simultaneously from both the top and bottom of the gel. Both of these new electrodes facilitated the formation of perpendicular protein band shapes and enhanced resolution at a comparable level. Due to their ease of use, double-deck electrodes are recommended. By combining these new electrodes with the field inversion gel electrophoresis (FIGE) technique, the protein bands could be focused and aligned nearly vertically, resulting in the highest level of electrophoretic resolution. Our electrodes are compatible with polyacrylamide gels of varying sizes, buffer systems, and sample well formats. They can be easily manufactured and seamlessly integrated into existing laboratory instruments for practical use.

Field Manipulation of Band Properties in Infrared Spectra of Thin Films

This comprehensive optical study analyzes field manipulations of bands in infrared (IR) spectra of thin films and functional surfaces for varying measurement and sample conditions. Band variations related to the materials dielectric functions, the measurement geometry, the film thickness as well as the direction dependence of the probing electromagnetic fields are demonstrated. Examples are discussed for isotropic polymer films (≈200 nm polymethylmethacrylate [PMMA]) on gold and silicon as well as an anisotropic hydrogen monolayer on a Si(111) surface, characterized by IR–attenuated total reflection, IR microscopy, and incidence‐angle‐dependent IR polarimetry. Even for fixed optical material properties, significant manipulations of band frequency and shape (shifts up to ≈14 cm−1 for PMMA, up to ≈3 cm−1 for H–Si) occur in not only polarization‐dependent but also unpolarized spectra. The shown data underline that polarimetric measurements and optical analyses are essential for a detailed interpretation of band shapes.

Photoemission Study of the Thermoelectric Group IV‐VI van der Waals Crystals (GeS, SnS, and SnSe)

AbstractGroup IV‐VI van der Waals crystals (MX, where M = Ge, Sn, and X = S, Se) are receiving increasing attention as semiconducting thermoelectric materials with nontoxic, earth‐abundant composition. Among them, SnSe is considered the most promising as it exhibits a remarkably high thermoelectric figure of merit (ZT), initially attributed to its low lattice thermal conductivity. However, it has been shown that the electronic band structure plays an equally important role in thermoelectric performance. A certain band shape, described as a “pudding mold” and characteristic for all MXs, has been predicted to significantly improve ZT by combining good electrical conductivity with high Seebeck coefficient. This subtle feature is explored experimentally for GeS, SnS, and SnSe by means of angle‐resolved photoemission spectroscopy. The technique also allows for the determination of the effective mass and Fermi level position of as‐grown undoped crystals. The findings are supported by ab initio calculations of the electronic band structure. The results greatly contribute to the general understanding of the valence band dispersion of MXs and reinforce their potential as high‐performance thermoelectric materials, additionally giving prospects for designing systems consisting of van der Waals heterostructures.

One-step synthesis of S-doped C-vacancy g-C3N4 with honeycomb porous nanosheets structure for efficient visible-light-driven hydrogen evolution

A defective construction method was applied to design the molecular framework from the source and use the intermolecular forces of the raw materials to connect the long chains. The S-doped honeycomb g-C3N4 nanosheets were prepared by selective volatilization at elevated temperatures using melamine-tricyanuric acid-thiourea supramolecular liquid as precursor and template. In addition to significantly increasing the high surface area, the S-doped honeycomb g-C3N4 nanosheets also modify the band gap structure and shape. The introduction of the C defect also increased the number of reaction sites, improved visible light responsiveness, broadened the photoresponse range, and accelerated the segregated transfer of photogenerated carriers. The experimental results showed that the hydrogen production efficiency of S-PDCN-3 (The best sample of S-doped C-vacancy g-C3N4) is 23.78 mmol‧g−1‧h−1, which was 21.8 times that of BCN, namely Bulk g-C3N4 (1.1 mmol‧g−1‧h−1). After adding the photosensitizer (Erythrosin B) to the photocatalytic reaction system, EB + S-PDCN-3 (the best sample of S-doped honeycomb g-C3N4 nanosheets with the sensitizer) precipitated hydrogen up to 63.8 mmol‧g−1‧h−1, which was 17.78 times greater than the hydrogen production of the EB + BCN sample (3.59 mmol‧g−1‧h−1). Furthermore, the sample was observed to experience a reduction in band gap energy, an increase in electron density near VB and a reduction of H* adsorption–desorption barrier, all of which are essential for the enhancement of the hydrogen evolution reaction. Successful preparation of S-doped honeycomb g-C3N4 nanosheets provides a simple and efficient method for developing efficient g-C3N4 photocatalysts—potential applications in the development process of hydrogen energy and pollutant degradation.

Effect of B2O3 addition on optical properties of Zirconium and Hafnium tetrafluorides in polycrystalline and thin film states

For the first time, the effect of B2O3 additive on the IR transmission spectra of ZrF4 and HfF4 samples and the optical properties of the coatings obtained from them was investigated. A significant difference in the shape of the absorption bands and the position of the vibration peaks of the Zirconium tetrafluoride and Hafnium tetrafluoride bonds was revealed. An assumption is made about the influence of ZrF4 polymorphism on the ratio of the vapor pressures of the specified compounds in the region of the conditional temperature of evaporation in a deep vacuum. The positive effect of the B2O3 additive on the rate of evaporation of system samples and condensation on substrates is shown. The values of the refractive indices of the coatings are about 1.53. An exception is the refractive index of the HfF4 coating (1.57), which can be attributed to the alternative (monoclinic) syngony of its crystal structure.