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We report on the formation of the field-effect transistor based on a polyyne–polyene structure. Polyvinylidene chloride (PVDC) drop casting and its subsequent dehydrochlorination in KOH solution allowed for the formation of porous polyyne–polyene material, which was analyzed via transmission electron microscopy, Fourier-transform infrared spectroscopy, and Raman spectroscopy, revealing the presence of sp- and sp2-hybridized chained fragments in the structure. The polyyne–polyene-based field-effect transistor showed a transconductance of 3.2 nA/V and a threshold voltage of −0.3 V. The obtained results indicate that polyyne–polyene-based transistors can be used as discrete elements of molecular electronics and that subsequent studies can be aimed toward the development of selective polyyne–polyene-based gas sensors with tunable sensitivity.

This work demonstrates the possibility of electrochemical formation of Ge-Sn-O nanostructures from aqueous solutions containing germanium dioxide and tin (II) chloride at room temperature without prior deposition of fusible metal particles. This method does not require complex technological equipment, expensive and toxic germanium precursors, or binding additives. These advantages will make it possible to obtain such structures on an industrial scale (e.g., using roll-to-roll technology). The structural properties and composition of Ge-Sn-O nanostructures were studied by means of scanning electron microscopy and X-ray photoelectron spectroscopy. The samples obtained represent a filamentary structure with a diameter of about 10 nm. Electrochemical studies of Ge-Sn-O nanostructures were studied by cyclic voltammetry and galvanostatic cycling. Studies of the processes of lithium-ion insertion/extraction showed that the obtained structures have a practical discharge capacity at the first cycle ~625 mAh/g (specific capacity ca. 625 mAh/g). However, the discharge capacity by cycle 30 was no more than 40% of the initial capacity. The obtained results would benefit the further design of Ge-Sn-O nanostructures formed by simple electrochemical deposition.

The formation of polyene-polyyne-based nanocomposites by dehydrohalogenation of the drop-cast-deposited polyvinylidene fluoride, assessment and ion-induced tailoring of their gas sensing properties are reported. The investigated structure was analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy and Fourier-transform infrared spectroscopy, revealing the thickness-dependent incomplete dehydrofluorination of the structure and its porosity induced by KOH treatment. The polyene-polyyne structures modified by low-energy Ar+ were studied by SEM and Raman spectroscopy, which showed the morphology variation, the shortening of chains and the graphitization of samples. The resistive gas sensing properties of the samples were analyzed at room temperature, revealing selective sensing of ammonia vapor by non-irradiated sample and the enhancement of the sensing properties for ethanol and water vapor after ion irradiation. With the ion dose enlargement, the change in the sensing response from electrical conductivity increase to decrease was observed for ammonia and ethanol, allowing us to discuss the origin and tunability of the sensing mechanism of the samples.

Using the methods of tunneling, infrared, X-ray photoelectron, Auger, and Raman spectroscopies, X-ray diffraction, and transmission electron microscopy, we study the structure and conductive properties of carbon films synthesized on various metal substrates (Al, Mo, Re, Ta, Ag, Cu, and Pt). The effect of the substrate material on the properties of the carbon film is studied. Based on non-empirical quantum-mechanical calculations, an analysis of the experimental vibrational spectra is carried out. The work function of the substrate material is concluded to depend on the length of the chain fragment.

The processes of femtosecond laser annealing of thin-film multilayer structures based on amorphous silicon and germanium produced by plasma-chemical deposition on a glass substrate have been studied. The formation of periodic structures on the surface of irradiated films has been detected by the scanning electron microscopy method. Analysis of Raman spectra has shown that amorphous germanium crystallizes and a mixing of germanium and silicon layers depending on the pulse energy density occurs in the absence of amorphous silicon layers crystallization as a result of exposure to femtosecond laser pulses.

Carbon films fabricated by pulsed-plasma ion-assisted sputtering of graphite in argon and nitrogen atmosphere are studied using Raman spectroscopy, electron diffraction, and X-ray photoelectron spectroscopy. The results show that nitrogen is efficiently incorporated in the material structure, which leads to formation of oriented graphite nanoclusters the amount of which increases with an increase in the assistance energy.

Nitronium borates of NO2[B(OX)4] type with X = CF3CO and NO2 as ligands were synthesized, and their structures were determined by powder X-ray diffraction. Crystalline NO2[B(ONO2)4] is relatively stable at room temperature and undergoes transformation to B2O3 upon heating. The [B(CF3COO)4]− anion was obtained for the first time and characterized as a structural fragment of a solid compound. The possibility of reversible modification of the complex anion by replacement of the nitrate or trifluoroacetate ligand was demonstrated for the first time by the mutual transformations of NO2[B(ONO2)4] and NO2[B(CF3COO)4].

ZnO single crystals doped with group-V elements have been grown from melt at high pressure. Dopants were introduced in several forms such as Sb2O3, P, As, Sb and Zn3X2 (X = P, As, Sb) in the high-pressure cell. Systematic studies of morphology were performed using optical microscopy and scanning electron microscopy. Crystal structure and lattice parameters were studied using X-ray diffraction and X-ray crystallography. Crystals exhibited distinct changes of size, shape and color compared to undoped ZnO melt-grown single crystals due to the dopants influence. X-ray photoelectron spectroscopy was used to determine valence states of group-V elements when incorporated in ZnO lattice. Photoluminescence, Raman spectroscopy and electron paramagnetic resonance spectroscopy were employed to investigate the nature of defects formed as the result of doping. Formation of VZn and VZn-complexes was confirmed and their concentrations were measured. Estimates of the number of VZn per one dopant atom showed that the ratio is noticeably higher than the one suggested for the shallow complex As(P, Sb)Zn-2VZn commonly regarded as responsible for acceptor properties in ZnO.

A commercial photopolymer used in 3D printers is studied using Raman spectroscopy. The Raman spectrum of an additive-manufactured part shows no lines at 1405 or 2992 cm–1, which are associated with the bending and stretching vibrations of C–H bonds and are present in the spectrum of the initial liquid photopolymer. That is, the vibrational spectrum changes after polymerization. This information may be of use for designing technological coatings based on the obtained samples.

The radiofrequency (RF) mild hyperthermia effect sensitized by biodegradable nanoparticles is a promising approach for therapy and diagnostics of numerous human diseases including cancer. Herein, we report the significant enhancement of local destruction of cancer cells induced by RF hyperthermia in the presence of degraded low-toxic porous silicon (PSi) nanowires (NWs). Proper selection of RF irradiation time (10 min), intensity, concentration of PSi NWs, and incubation time (24 h) decreased cell viability to 10%, which can be potentially used for cancer treatment. The incubation for 24 h is critical for degradation of PSi NWs and the formation of silicic acid ions H+ and H3SiO4- in abundance. The ions drastically change the solution conductivity in the vicinity of PSi NWs, which enhances the absorption of RF radiation and increases the hyperthermia effect. The high biodegradability and efficient photoluminescence of PSi NWs were governed by their mesoporous structure. The average size of pores was 10 nm, and the sizes of silicon nanocrystals (quantum dots) were 3-5 nm. Degradation of PSi NWs was observed as a significant decrease of optical absorbance, photoluminescence, and Raman signals of PSi NW suspensions after 24 h of incubation. Localization of PSi NWs at cell membranes revealed by confocal microscopy suggested that thermal poration of membranes could cause cell death. Thus, efficient photoluminescence in combination with RF-induced cell membrane breakdown indicates promising opportunities for theranostic applications of PSi NWs. �� 2019 American Chemical Society.

The method of ion-plasma pulse-arc sputtering of graphite in a methane atmosphere has been employed to produce carbon films with different rate of sp1-bonds having a significant impact on the electrical conductivity of those films. Raman spectroscopy showed that the line near 2040 cm−1, corresponding to the oscillation of long carbon chains with sp1-hybridization, became more prominent with increase of methane concentration in the vacuum deposition chamber. The obtained spectra revealed multiphonon replicas of the 2040 cm−1 line that is evidently associated with the presence of defects in carbon chains.

The results of a study of copper chromite ceramic samples doped with magnesium are presented. The samples were synthesized according to the solid-phase method using a special procedure for preparing the initial mixture, which ensures a uniform distribution of magnesium with its content from 0.2 to 6%. The substitution of chromium for magnesium in the crystal lattice is confirmed by Raman scattering of light and EPR spectra. As the magnesium content increases from 0 to 6 at.%, the resistivity of the synthesized samples decreases by more than 3 orders of magnitude at room temperature. High thermopower values were obtained, and it was shown that the main charge carriers are holes, and the predominant mechanism of hole transport in doped samples is hopping transfer over localized states, whose density decreases with an increase in energy near the Fermi energy. It is shown that the localization radius increases with an increase in magnesium content.

We present experimental data on the strength of filaments in the para-aramid fiber Taparan for gage length 10, 20, 30, and 40 mm. A nonlinear multiplicative model is used to represent the relationship between the properties. The coefficients of the model are determined from experimental data. The critical length is calculated for a single filament in the Taparan fiber. The multiplicative model is used to predict the strength properties for filaments of critical length.

In this work the optical properties of carbidized silicon nanowires (SiNW) are investigated.

Linear-chain carbon films with a thickness of order 100 nm were studied by tunneling spectroscopy. The oscillating dependence of the differential conductivity of the investigated structures is established. The results obtained are interpreted using a model of charge-density wave formation in regular structural kinks of carbon chains. The Raman spectra of the films are recorded. The simulated spectra of harmonic oscillations of polyines (–C≡C–) n and cumulenes (=C=) n of carbon films are theoretically compared.

The Raman spectra of kinked carbon chains with a set of end groups composed of hydrogen, silver, and copper atoms are calculated. It is analyzed how end groups, as well as the positions of impurity atoms in the chain, affect shifts characterizing the main peaks of the harmonic vibrations of chemical bonds between carbon atoms in polyyne- and cumulene-like (respectively, (–C≡C–) n and (=C=) n ) chains.

In this paper, the layers of quantum silicon nanowires produced on highly-doped wafers were studied via the Raman spectroscopy and IR reflection spectroscopy methods. The porosity of layers of different thickness has been determined from IR spectroscopy data using the Bruggeman effective medium model. According to Raman spectroscopy data, the concentration of the free charge carriers in quantum silicon nanowires drops in comparison with that in the wafer. On the basis of these results we conclude that the thickness of a quantum nanowires layer of 2 μm is optimal for its use as an antireflection coating in solar cells. Layers with thicknesses of 10 and 15 μm were studied. It was demonstrated that there is no effect of Raman-scattering enhancement in these layers.

Germanium (Ge) nanowires were fabricated by electrochemical deposition on titanium-coated silicon substrate. Arrays of nanowires with different mean diameters were obtained using indium nanoparticles of various sizes as centers of nucleation. Raman spectroscopy was used to establish the structural properties of nanowires under different laser excitation intensities. Cycles of measurements with different intensities demonstrated irreversible changes in the structure. Initial study with minimal excitation intensity of 3 W/cm2 displayed that the spectra are descriptive of amorphous Ge. Further study at increased intensities led to the transformation of Raman spectra to the shapes that can be attributed to crystalline Ge. Detailed analysis of spectra shapes for samples with different mean diameters of Ge nanowires after exposure to high intensity laser radiation allows to estimate the fraction of the crystalline phase in Ge nanowires. The spectra of a sample irradiated by He–Ne laser were compared with thermally annealed sample in a vacuum at 150 °C. A similar shape of the obtained spectra indicates on the thermal nature of the effect, which leads to a change in the observed structural properties. This change under even slight heating can be explained by thermal isolation of nanowires from the substrate.

We present a modified approach to the synthesis of sp-based films. This technique includes two stages: the dehydrohalogenation of polyvinylidene chloride powder and its subsequent sputtering. The synthesized films were characterized by Raman spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray excited Auger electron spectroscopy. The films were shown to consist of sp-hybridized carbon chains and nanocrystalline graphite. Sp-carbon evaporation and sp-hybridized clusters sputtering mechanisms leading to sp-clusters transfer from an sp-rich target to the growing film surface were discussed.

Amorphous carbon structures containing silver nanoparticle inclusions were synthesized by ion-assisted pulse-plasma deposition. Coatings were investigated by transmission electron microscopy, electron diffraction, electron energy loss spectroscopy, Raman spectroscopy and ultraviolet-visible (UV-Vis) absorption spectroscopy. Ion assistance energy variation was found to affect silver nanoparticles shape, carbon matrix composition and clustering. UV-Vis absorption spectra dependence on the structural changes was discussed.

Quantitative characteristics of the interrelation between the strength characteristics of filaments of the aramid fibers tvaron and taparan and a copolymer fiber are determined. The parameters of the linear regression model are determined. It is shown how a variation in one property may vary the other properties. For the copolymer para-aramid fiber and tvaron fiber, the work of disintegration of a filament does not have any effect on the ultimate strength. Examples are presented that illustrate how to use regression relationships to predict a variation of the strength characteristics once one of the basic technological characteristics, that of linear density, varies.

The paper presents the results of increasing the strength and modulus of single filaments and yarns of a paraaramid fiber by their processing with an aqueous suspension of carbon nanotubes in the production process

Silicon-carbide (SiC) nanowire structures 40–50 nm in diameter are produced by the high-temperature carbonization of porous silicon and silicon nanowires. The SiC nanowires are studied by scanning electron microscopy, X-ray diffraction analysis, Raman spectroscopy, and infrared reflectance spectroscopy. The X-ray structural and Raman data suggest that the cubic 3C-SiC polytype is dominant in the samples under study. The shape of the infrared reflectance spectrum in the region of the reststrahlen band 800–900 cm–1 is indicative of the presence of free charge carriers. The possibility of using SiC nanowires in microelectronic, photonic, and gas-sensing devices is discussed.

The elasticity modulus of Rusar-NT aramid fiber was increased after electromagnetic treatment (EMT). A fiber sample was treated immediately after it was prepared and did not undergo additional chemical processing. The tensile strength increased by almost 20%; elasticity modulus, 11.48%. A comparison of IR and Raman spectra found that several spectral lines were shifted after EMT of the fiber.

Single filaments of aramid complex thread were observed to have improved strength. Threads were treated during fabrication with an aqueous suspension of Taunit multi-walled carbon nanotubes. The average strength increased by 10.66%; minimal strength, by 31.68%.

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Porous Ge layers of nanowires were formed by low energy (30 keV) Ag+ ion implantation of crystalline c-Ge substrate. Different radiation doses resulted in the formation of nanowires with various mean diameters. The obtained layers were studied by Raman spectroscopy using helium-neon and argon exciting lasers at wavelength of 633 and 488 nm respectively. It was demonstrated that implanted amorphous layers were locally crystallized by the lasers. The crystallization thresholds were found to be 3 kW/cm2 for helium-neon exciting laser and 1 kW/cm2 for argon exciting laser. The variation of thresholds is suggested to be due to the different light penetration depths at these wavelengths in Ge. The crystalline volume fraction was determined and reached maximum value of 6–7%, the divergence of which can be explained by the difference in the distribution of Ge nanowire diameters.

The results of electromagnetic treatment (EMT) of Rusar NT aramid fibre, which increased the ultimate strength and elasticity modulus by 8-10%, are reported. The theoretical possibility of enhancing strength properties of Rusar NT fibre up to 20% by EMT is shown. The measurements were systematized by cluster analysis. It is suggested that the hydrogen bond is strengthened upon EMT, which ultimately leads to improvement in strength properties of Rusar NT fibre.

IR and Raman spectra of the aramid fibers Kevlar, Twaron, Heracron, Taparan, and Rusar NT that were produced under identical conditions are presented. It was found that spectra of the fibers could be combined into two groups of Kevlar-Twaron-Taparan and Heracron-Rusar NT. The collections of C–H stretches in the range 2500-3100 cm–1 were unique for each fiber due to processing specifics.

An ordered array of silicon dioxide pyramids were obtained in the course of silicon substrates etching in viscous solution of dimethylformamide. Systematic study was made to establish the influence of etching current and solution composition on the size, density and the shape of SiO2 pyramids. In general, the formation of the structure involves following steps: (i) the porous silicon layer formation at the interface with monocrystalline silicon, (ii) a sol-gel synthesis of the porous SiO2 area on top of the por-Si layer, (iii) formation of cracks in the por-Si layer and (iv) dissolution of the por-Si layer and as consequence the growth of the Si/SiO2 pyramids. The photoluminescence properties of the samples (λex = 405 nm) are determined by morphology of pyramids array.

This work is dedicated to the influence of thermal treatment procedures in vacuum and air atmosphere on the structural features of multiwalled TiO2 anodic nanotubes (NTs) formed in fluorine-containing ethylene glycol (EG) based electrolyte investigated by high-resolution transmission electron microscopy (HRTEM) in conjunction with EDX and electronic nanodiffraction (STEM nanodiffraction), IR and Raman spectroscopy, XPS and ToF SIMS. Using electron nanodiffraction technique, there were estimated TiO2 nanocrystallite sizes for the inner layer of the NTs after annealing in air and vacuum for the first time. The differences in carbon distribution profiles in TiO2 nanotube crosscut after thermal treatments in air and vacuum were discussed. It was found that thermal treatment in vacuum leads to different phase composition of TiO2 NTs IL comparing to annealing in air. A sequential thermal treatment (firstly in vacuum and then in air) enables to remove carbon from TiO2 NTs surface and partly from TiO2 NTs IL and prevent detachment of IL from OL at the same time. The obtained data will be useful for understanding the mechanisms of structural modifications during thermal treatments as well as for functional properties optimization of such nanostructures.

Raman spectroscopy was applied to investigate laser-induced heating of silicon nanowires (SiNWs) formed by metal-assisted chemical etching of lightly boron-doped crystalline silicon (c-Si) wafers. Low-frequency shift of the Raman peak from 520.5 cm−1 to about 517 cm−1 for SiNWs with length of 40–65 µm under laser irradiation with wavelengths of 632.8 or 488 nm was observed, and it was explained by an increase in the average temperature of SiNWs on about 150 K for the laser intensity about 1 kW/cm2. The same photoinduced heating was confirmed by analyzing the ratio between the Stokes and anti-Stokes components of the Raman scattering. The obtained experimental data allow us to estimate the thermal conductivity coefficient of SiNW array ~0.1 W/(m K), which is three orders of magnitude smaller than that of c-Si. Furthermore, the Raman spectra of SiNWs under excitation with intensity above 0.2–0.5 kW/cm2 consisted of an additional low-frequency peak, which is related to an overheated subsystem of well spatially separated fine SiNWs up to 600–700 K. The observed strong photoinduced heating can be used for local laser-induced treatment of SiNWs and biomedical applications.

The strength properties of filaments and a basalt fiber roving of industrial production were investigated at different clamping lengths and deformation rates. The deformation rate for filaments was varied from 1 to 20 mm/min, but the clamping lengths selected were 10, 20, 30, and 50 mm. No clamping-length-dependence of strength parameters of the roving in the range of 350-600 mm was detected. The results found for basalt fiber filaments were compared with published data for Kevlar29 aramid, T300 carbon, and Advantex glass fiber filaments.

Nanocrystalline silicon stabilized by butyl and perfluorobutyl ligands that form improper surface states of silicon nanocrystals were synthesized. The presence of perfluorobutyl ligands on the surface of silicon nanocrystals was proved by IR spectroscopy. Nanocrystals with perfluorobutyl ligands form aggregates, which decreases the efficiency of photoluminescence. The nanocrystals with butyl ligands have smaller size but their photoluminescence can be clearly recorded.

Changes in the IR spectrum of a pretreated polyethylene film during resonant irradiation by a weak electromagnetic field were measured for the first time.

The modification of boron-doped amorphous hydrogenated silicon films [a-Si:H(B)] with femtosecond laser radiation is studied in this work. It is demonstrated that femtosecond laser crystallization of the a-Si:H(B) film area leads to extremely high values of the free charge carrier (hole) concentration, which is typical for degenerated semiconductors. The free charge carrier concentration is locally determined by measuring the Raman spectra in the modified areas. The shape of Raman spectra is typical for Fano resonance. It is found that the charge carrier concentration in the modified areas may exceed 1020 cm−3 depending on the femtosecond irradiation conditions. The areas with such a high concentration of free charge carriers are also characterized by high volume fraction of crystalline phase (more than 90%). Such a sharp increase in the free charge carrier concentration in the modified areas may be explained by an increase in concentration of electrically active boron atoms. The activation energy of the temperature dependence of the conductivity for laser beam treated areas is in full agreement with the data obtained from the analysis of the Raman scattering spectra.

Infrared spectroscopy is used to investigate the effect of ammonia adsorption on the concentration of equilibrium charge carriers in porous-silicon layers with various initial types of dopants at different concentrations. It is found that ammonia adsorption from aqueous solution results in an increase in the concentration of free electrons in n -type samples up to a level exceeding 1018 cm–3. In p -type samples, a nonmonotonic dependence of the charge-carrier concentration on ammonia pressure is observed. The obtained results are explained by the appearance of adsorption-induced shallow donor states that, along with the initial-dopant and surface-defect states, determine the charge-carrier type and concentration in the silicon nanocrystals of the porous layer after ammonia adsorption. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)