The subthreshold swing S is a fundamental characteristic of MOSFET transistors [1]. It shows how many times the gate voltage Vg must be increased in the subthreshold range in order to achieve an increase in the drain current Id by an order of magnitude: $S \equiv \ln(10) \frac{dV_g}{d\ln(Id)}$.At room temperature in a high-quality transistor with a large value of sub-gate capacitance, the...
Raman spectroscopy is a fast, sensitive, and non-destructive technique for characterization of structure, phonon spectrum and even some electronic properties of semiconductors and isolators. In exploring semiconductor nanostructures and heterostructures, this technique benefits from possibility to tune the excitation wavelength to selectively excite parts of the material with different...
Multiferroic materials, which exhibit multiple ferroic orders simultaneously, have garnered significant scientific interest thanks to their potential for electric-field control of magnetism. These materials present unique domain formations and poling behavior under external fields. Here, we will showcase a remarkable reversible transfer of domain patterns between magnetization and...
Soft X-ray ptychography is a scanning coherent diffractive imaging technique employed at synchrotron facilities. It relies on collecting diffraction patterns from overlapping illumination spots of the sample. Spatial resolutions in the order of 5 nm are achievable and ferroic order can be visualised by dichroic contrast with circularly or linearly polarised soft X-rays at the 3d transition...
The physics of electric-field-induced phase transitions in ferroelectric materials has attracted considerable attention for promising future use in a variety of new-generation electronic devices. Even more, control of the antiferroelectric-ferroelectric phase transition of antiferroelectric thin films is necessary for highly efficient data storage, sensing, and energy harvesting applications....
The development of environmental sensitive fluorescent nucleoside analogues (FNA) to site-selectively characterize the structure and dynamics of nucleic acids is of high demand [1]. One of the perspective FNA is isothiazologuanosine (tzG) [2], an isomorphic and isofunctional FNA of guanosine (G). tzG can faithfully substitute G in non-canonical nucleic acid structures. tzG spectroscopic...
Drug delivery is a method of administering a drug to achieve a therapeutic effect in humans or animals [1]. Over the past two decades, many ways to create controlled drug delivery systems have emerged, among which systems based on plasmonic metals, particularly gold, stand out. Due to their bioinertness, ability to be heated under laser irradiation at different wavelengths depending on size...
This report presents the results of recording the non-thermal effect of millimeter waves on the fluorescence of an aqueous solution of rhodamine 6G. At low concentrations of dye molecules, normal temperature quenching of fluorescence is observed: its intensity decreases with increasing temperature. However, solutions with high dye concentrations show the opposite effect: with increasing...
In this study, we investigated the relationship of BSA (Bovine Serum Albumin) protein with thiochrome dye through several spectroscopic techniques, including absorption, IR, and Raman spectroscopy.
Since BSA is a multifunctional plasma protein that carries a huge number of compounds, in this study we have chosen a dye that has good spectral properties and can detect conformational changes in...
The application of self-similarity principle is shown in the example of utilizing a system of self-similar difference equations for processing spectral data, in particular the processing luminescence spectrum of quantum dots (Gaussian peak) as well as the kinetics of luminescence decay.
For the spectrum of quantum dots, the relationship between the parameters of the Gaussian function and the...
Surface-Enhanced Raman Spectroscopy (SERS) has been increasingly gaining popularity as a promising spectroscopic tool for detection and identification of trace amounts of various molecular species [1]. The level of sensitivity claimed by many groups various types of substrates and analytes in the impressive pico- to femto-molar concentration range. However, the no wide commercialization of the...
Incorporation of colloidal NCs in polymer matrices is a way to tailor NC properties and to protect NCs from degradation under the influence of ambient. Investigation of luminescent NCs in optically transparent polymers is important in view of perspective applications in photonics, while composites of NCs and conductive polymers can be promising for photovoltaics, electroluminescence, and...
The quaternary semiconductor Cu2ZnSnS4 (CZTS) and related compounds is a promising material for photovoltaic applications, thermoelectric and other applications related with alternative energy conversion and storage [1]. Significant research efforts have been made to obtain CZTS with superior structural quality, as well as the development of more efficient characterisation techniques for the...
The theses will be submitted later
Stimulated Raman backward scattering of a laser beam propagating in a homogeneous plasma is investigated in the presence of static magnetic field. The laser decays into an upper hybrid wave and a down-shifted sideband wave as it travels through plasma. A non-linear ponderomotive force acts on the plasma electrons which drives the excited upper hybrid wave. The upper hybrid wave couples with...
The use of mechanochemical activation of metal powders and their mixtures in planetary mills opens wide prospects for the creation of new nanocomposite materials. Mechanochemical synthesis provides the possibility of obtaining a uniform distribution of the dispersed phase, of expanding the solubility limits of elements, of reducing the grain size to the nanoscale, and of obtaining new...
Quantum-chemical calculations (by DFT method in B3LYP/cc-pVTZ approximation) of optimal structure and vibrational spectra of water and methanol clusters in different media were carried out using Gaussian 09 software. Water clusters consisting of from one to six molecules in vacuum, water and argon media were considered. By comparison of the calculated IR absorption spectra of clusters in...
The heterostructures of $\text{Cr}_{1}\text{Ag}_{45}\text{TiO}_{2}$, $\text{Cr}_{1.2}\text{Cu}_{40}\text{TiO}_{7}$, and $\text{Cr}_{1.2}\text{Cu}_{43}$, prepared by chemical vapour deposition method were investigated using ellipsometric measurement method in order to calculate optical constants by two models namely Tautz-Lorentz and the effective medium model at the vicinity of the principal...
The potential of Zinc oxide (ZnO) nanophosphor material as a host for optoelectronic applications was investigated in this study. ZnO nanoparticles were synthesized using the co-precipitation method, followed by sintering at a maximum temperature of 700°C in air. The sintering process was carried out in a custom-made temperature-controlled muffle furnace with a precision of ±1°C, reaching a...
The Heavy Atom Effect on Spectro-Optical Properties of Pi-electron Containing Molecular Complex Based on Tryptanthrin
Nazarii V. Tkach, Vladislav Yu. Kudrya, Antonina P. Naumenko
Faculty of Physics, Taras Shevchenko National University of Kyiv, 64/13 Volodymyrs’ka str., 01601 Kyiv, Ukraine
Tryptanthrin is a naturally occurring indoloquinazoline alkaloid...
The study of the interaction of nanoparticles and complexes with phospholipid membranes is an important stage of research, since they can be of potential importance for biological applications. Phospholipid membranes serve as an important model for studying the reaction to the introduction of the objects under study, as they are characterized by their simplified structure.
In our study, we...
Recent advancements in multi-energy X-ray computed tomography (CT) have garnered significant attention in non-destructive testing (NDT), allowing the segmentation of materials based on variations in X-ray absorption spectra across different energy bands. This study explores integrating multi-energy X-ray CT data with mixed reality (MR) technology to provide a spatial representation of internal...
Polarization poses a significant challenge in cadmium telluride (CdTe) detectors, preventing the simultaneous achievement of high energy resolution and long-term stability at room temperature. The mechanism driving bias-induced polarization is presumed to involve an increase in the number of ionized acceptors resulting from hole detrapping. Simultaneously, the accumulation of negative charges...
Thallium Bromide (TlBr) is a compound semiconductor with a wide band gap(2.68 eV). TlBr can be formed into thin films by vacuum evaporation, and large areas can be produced without a tiling process. TlBr is potentially suitable for FPD applications.
TlBr thin films deposited by vacuum evaporation was evaluated. In direct conversion semiconductor detectors, the quality of the semiconductor...
Demand for nondestructive testing using X-ray imaging is increasing, and it is used in a variety of situations to identify defects and damage in precision equipment. In X-ray imaging, it is difficult to accurately position the X-ray source, object, and detector on the irradiation axis because the trajectory of the X-rays is impossible to see with the human eye. In this research, we propose a...
TlBr (thallium bromide) is one of the materials used in semiconductor detectors.
Due to its characteristics, it is generally being researched as a semiconductor detector for
high-energy X-rays that can operate at room temperature, but it suffers from low carrier
mobility and a reduction in energy resolution due to signal rise time. Therefore, we will
consider fabricating a semiconductor...
CdTe used as a semiconductor detector has the advantages of high sensitivity to high energy and the ability to operate at room temperature. However, its charge collection efficiency is lower than that of Si and Ge. To ensure sufficient charge collection efficiency, it is desirable to use a structure that allows the application of high voltages. Therefore, when used as a CdTe detector, it is...
Backscattered X-ray imaging is a non-destructive inspection technique that uses X-rays scattered back from an object. Compared to X-ray transmission imaging, backscatter X-ray imaging has the advantage that the source and detector can be placed on the same side of the object and is used for inspection of thick objects and structures. However, due to the high attenuation of X-rays by soil, it...
CdTe is an excellent material for semiconductor X-ray detectors that can be operated at room temperature, but its K-edge around 30 keV results in a low line attenuation coefficient in the lower energy region. We propose gallium nitride (GaN) as a new semiconductor detector material, which has a higher linear attenuation coefficient than CdTe in the low energy region of about 10 to 26 keV and...
In recent years, the concern over the insecure supply of minor metals such as tantalum in Japan has prompted recycling from waste materials such as printed circuit boards.Techniques have been developed to strip metal parts from printed circuit boards, but it is difficult to completely separate parts containing a wide variety of metals, and some loss is incurred.Therefore, we propose a method...
X-ray backscattering emerges as a pivotal technique in the realm of subsurface exploration, offering a non-invasive approach to material characterization beneath the soil. This method is significant due to its ability to provide detailed insights into the composition and structure of buried materials without direct physical contact, a feature crucial in fields like geology and environmental...
