Optical and Magnetooptical Spectroscopy of the Nanostructural Multilayered Films: Possible Applications

The aim of the paper is to show the potential of the spectroscopic ellipsometry and magnetooptical (MO) spectroscopy for probing of the multilayered films (MLF) with sublayer thickness of about a few nanometres. The main approach applied by us is based on the comparison of the experimental optical and MO properties with the simulated ones based on various models of the MLF. Specifically, as shown, such an approach can be useful for studying the nature of unusual MO properties and the interfaces in MLF comprising the noble and 3d-transition metals (3d-TM). The high sensitivity of the applied spectroscopic methods for the monitoring of the solid-state reactions in the 3d-TM/Si MLF induced by ion-beam treatment or by thermal annealing is also demonstrated. The optical properties of various silicides formed spontaneously or induced by various treatments at interfaces are evaluated experimentally and compared with the results of first-principle calculations.В данной работе показаны возможности спектральной эллипсометрии и магнитооптической (МО) спектроскопии для изучения структуры и особенностей физических свойств многослойных металлических пленок (МСП) с толщинами составляющих слоев порядка единиц нанометров. Основной подход исследования базируется на сравнении экспериментально измеренных оптических и МО свойств МСП с модельными, полученными для различных моделей структуры МСП. Было показано, что данный подход позволяет выяснить природу необычных МО свойств, а также структуру интерфейсной области в МСП, состоящих из слоев благородных и 3d-переходных металлов (ПМ). Также в работе продемонстрирована высокая чувствительность спектральной эллипсометрии для изучения твердотельных реакций в МСП 3d-ПМ/Si, вызванных ионной бомбардировкой или термическим отжигом. Оптические свойства различных силицидов 3d-ПМ, сформированных спонтанно либо в результате различных воздействий на МСП, были изучены экспериментально и сравнены с результатами теоретических первопринципных расчетов.В даній роботі показані можливості спектральної еліпсометрії та магнітооптичної (МО) спектроскопії для вивчення структури та особливостей фізичних властивостей багатошарових металевих плівок (БШП) з товщинами складаючих їх шарів порядку одиниць нанометрів. Основний підхід дослідження базується на порівнянні експериментально одержаних оптичних та МО властивостей БШП з модельними, що були одержані для різних моделей структури БШП. Було показано, що даний підхід дозволяє визначити природу незвичайних МО властивостей, а також природу інтерфейсної області БШП, що складаються з шарів благородних та 3d-перехідних металів (ПМ). В роботі також паказана висока чутливість спектральної еліпсометрії для вивчення твердотільних реакцій в БШП 3d-ПМ/Si, зумовлених іонним бомбардуванням або термічним відпалом. Оптичні властивості різних силіцидів 3d-ПМ, що було зформовані спонтанно або завдяки зовнішньому впливу, були вивчені експериментально та порівняні з результатами теоретичних першопринципних розрахунків

Multilayer film heterostructures. Silicides

The formation of heterostructures based on nanoscale silicide films in limiting states are exemplified. The nanoscale silicide films of a required phase composition are shown to be obtainable by formation of specific zones, different type interlayers referred to as the diffusion-controlling layers between the metal layer and substrate (silicon single crystal).Подано приклади отримання гетероструктур на основі нанорозмірних силіцидних плівок у граничних станах. Показано, що отримання нанорозмірних силіцидних плівок необхідного фазового складу забезпечується формуванням між шаром металу і підкладкою (монокристалом кремнію) особливих зон, прошарків різного типу - дифузійноконтролюючих шарів.Показаны примеры получения гетероструктур на основе наноразмерных силицидных пленок в предельных состояниях. Показано, что получение наноразмерных силицидных пленок необходимого фазового состава обеспечивается формированием между слоем металла и подложкой (монокристаллом кремния) особенных зон, прослоек разного типа - диффузионно-контролирующих слоев

Ellipsometric evidence of CoSi₂ formation in Co/Si multilayer induced by thermal annealing

The work aim is to demonstrate the potential of the spectroscopic ellipsometry (SE) approach to study the solid state reactions, both spontaneous and/or induced by thermal annealing, in (3.0 nm Co / 10.6 nm Si)₂₀ multilayered film (MLF). The regions with a stoichiometry close to Co₂Si are supposed to be formed spontaneously in the asdeposited Co/Si MLF. Sequential anneals of Co/Si MLF at 400, 600, and 700℃ do not produce any visible changes in their amorphous-like large-angle X-ray diffraction (HAXRD) spectra, while the SE indicates the formation of regions with a stoichiometry close to CoSi. Independently on the HAXRD results, the conclusion on the formation of CoSi₂ phase induced by annealing of Co/Si MLF at 800℃ can be confidently done on the basis of only optical study.Целью работы является демонстрация возможностей спектроскопической эллипсометрии (SE) при исследовании твердофазных реакций (как самопроизвольных, так и индуцированных) в многослойной пленке (MLF) (3,0 нм Co / 10,6 нм Si)₂₀. Предполагается, что в свежеосажденной области Co/Si MLF самопроизвольно образуются области со стехиометрией, близкой к Co₂Si. Последовательный отжиг Co/Si MLF при 400, 600 и 700℃ не вызывает видимых изменений в спектрах широкоугловой дифракции рентгеновских лучей (HAXRD), в то время как SE выявляет образование областей со стехиометрией, близкой к CoSi. Независимо от результатов HAXRD, на основании только оптических исследований можно сделать надежный вывод об образовании фазы CoSi₂ под влиянием отжига Co/Si MLF при 800℃.Метою роботи є демонстрацiя можливостей спектроскопiчної елiпсометрiї (SE) при дослiдженнi твердофазних реакцiй (як спонтанних, так i iндукованих) у багатошаровiй плiвцi (MLF) (3,0 нм СО/10,6 нм Si)₂₀. Припускається, що у свiжоосадженiй областi Co/Si MLF спонтанно утворюються областi зi стехiометрiєю, близькою до Co₂Si. Послiдовний вiдпал Co/Si MLF при 400, 600 i 700℃ не викликає видимих змiн у спектрах ширококутової дифракцiї рентгенiвських променiв (HAXRD), у той час як SE виявляє утворення областей зi стехiометрiєю, близькою до CoSi. Незалежно вiд результатiв HAXRD, на пiдставi тiльки оптичних дослiджень можна зробити надiйний висновок про утворення фази CoSi₂ пiд впливом вiдпалу Co/Si MLF при 800℃

Variation of abundance and demographic structure of the introduced pumpkinseed, Lepomis gibbosus (Actinopterygii: Perciformes: Centrarchidae), in relation to littoral habitats and water body use

Background. The pumpkinseed, Lepomis gibbosus (L.), is one of 23 introduced fish species in Bulgarian freshwaters. With this study we attempt to contribute to clarifying the factors that effect pumpkinseed abundance and demographic structure in water bodies differing in macro- and microhabitat parameters. Materials and methods. Fish were collected during the breeding period of pumpkinseed (May–June 2010) by minnow traps arranged in 31 sites in the littoral zone of 13 fresh water bodies (former- and active sand-pit lakes, reservoirs, adaptive ponds of refineries). Demographic structure (length and age) and abundance (Catch Per Unit Effort; CPUEN; fish per trap per hour) of pumpkinseeds from different sites were compared to provide information about ecological requirements of this species. Results. L. gibbosus dominated at 24 sites and comprised 86.7% of all fish caught. The mean pumpkinseed abundance was 6.35 ± 7.2 fish per trap per hour (mean ± SD). Pumpkinseeds were most numerous in the littoral zones of the former sand-pit lakes, where pumpkinseed’s CPUEN achieved values of 20 fish per trap per hour. Water body use had a significant effect on pumpkinseed abundance and the statistical analyses revealed that the littoral zones in the active sand-pit lakes were characterized by the lowest number of pumpkinseeds than the other types. Microhabitat parameters such as silt and sand bottom substrate also significantly affected pumpkinseeds abundance, size, and age, while gravel significantly affected body length but not abundance and age. Aquatic vegetation also had a significant impact on the abundance and at sites with dense vegetation pumpkinseeds were more abundant than at the sites with sparse vegetation. At the sites where piscivore fish occurred, the mean length and mean age of pumpkinseed were lower. Conclusion. Human activities facilitate establishment of the pumpkinseed population, mainly by extending suitable breeding places for pumpkinseed and eliminating its natural competitors and predators. Some parameters as sand or silt bottoms in littoral area and dense submerged vegetation may use as indicator of suitable conditions for pumpkinseed

Productivity of Holsteinized black-and-white cattle depending on age

The Ural type of the domestic black-and-white breed is characterized by high productivity and good suitability for use in the conditions of industrial milk technology. During its breeding, the use of purebred bulls-producers of the Holstein breed of both domestic and foreign breeding continues. As a result of the conducted research, it was found that the productivity of cows changes significantly with age. Milk yield for 305 days of lactation increases from 1 lactation to 3 lactation, and then decreases by 369 kg or 3.8% in the fourth, relative to the third, and by 2090 kg or 22.2% in the fifth, relative to the fourth. The productivity of full-aged cows is higher than that of young cows and can remain at a high level for a long period. The quality indicators of milk changed upward from the first to the fifth lactation. High correlation coefficients were established by the conjugation of milk quality indicators with each other, regardless of lactation. They ranged from 0.364 (2 lactation) to 0.533 (1 lactation). That is, a decrease or increase in MJ in milk will lead to the same change in MDB

Mitigation of cyber risks in the field of electronic payments: Organizational and legal measures

The issues of ensuring the electronic payments’ security are currently in the limelight of participants in the monetary system and the scientific expert community. The goal of this paper is to develop organizational and legal measures aimed at improving the security of electronic payments in the Russian Federation. Research methods include the analysis of retrospective data describing the development of the payment system and electronic payments using bank cards, as well as the method of statistical observations and analysis of secondary data from surveys of Russian and foreign companies covering the information security. Through solving the research problems, the author managed to draw a number of conclusions: ∎ Dynamic development of the electronic payment system causes the growth of cybercrime and cyber risks in payment systems; ∎ Despite quite active actions of state bodies and the Bank of Russia, the legal framework and infrastructure for electronic payments are still in the development stage; ∎ Cyber attacks cause significant damage not only to financial institutions, but also to companies from a non-financial sector, as well as to ordinary citizens using electronic payment systems. In the opinion of the author, the key organizational and legal measures aimed at mitigating cyber risks in electronic payments may be measures to form the centralized payment infrastructure of the Bank of Russia, introduce the corporate cyber threat management systems, improve policies and procedures for the protection of personal data at the corporate level, as well as train the employees in the field of information security of electronic settlements. © 2018, ASERS Publishing House. All rights reserved

Formation and thermal stability of NiSi phase in Ni (30 nm)/Pt (2 nm; 6 nm)/Siep. (50 nm)/Si (001) thin film systems

The influence of Pt on solid state reactions in Ni (30 nm)/Pt(x) /Siep.(50 nm)/ Si (001) (x=2 nm, 6 nm) nanodimensional films has been investigated. The layers of Pt and Ni were produced by magnetron sputtering technique on the epitaxially grown 50 nm Si layer on the top of the monocrystalline Si (001) substrate at the room temperature. Isochronal rapid thermal annealing of the samples was carried out in nitrogen atmosphere for 30 s in (450—900)° C temperature range. In the as-deposited films no phase formations were observed. During heat treatments thermally activated solid state reactions began by formation of intermediate silicide phase of Ni₂Si for x=2 nm, but the formation of this Ni reach phase was hindered for x=6 nm. Increasing the annealing temperature up to 600° C, independently from the thickness of the intermediate Pt layer, NiSi , PtSi compounds as well as Ni₁₋xPtxSi solid solution have been formed. Two-layered heterostructure has been observed for x=6 nm: complex polycrystalline Ni₁₋xPtxSi phase formed close to the surface, below which the NiSi phase was situated. Decomposition of Ni₁₋xPtxSi silicide to the NiSi (and PtSi ) phases was observed after annealing above 650° C and 850° C. Si enrichment at the surface of the Ni₁₋xPtxSi , NiSi and NiSi₂ phases is clearly observed on secondary neutral mass spectrometry depth profiles, which is interpreted as a consequence of the fast diffusion of Si along the grain boundaries

Water-soluble triazole chitin derivative and its based nanoparticles: Synthesis, characterization, catalytic and antibacterial properties

In this work, we treated chitin with 2-(azidomethyl)oxirane and successfully involved the resultant azido chitin derivatives in the ultrasound-assisted Cu(I)-catalyzed azido-alkyne click (CuAAC) reaction with propargylic ester of N,N,N-trimethyl glycine. Thus, we obtained novel water-soluble triazole chitin derivatives. The triazole chitin derivatives and their nanoparticles are characterized by a high in vitro antibacterial activity, which is the same or even higher than that of commercial antibiotics ampicillin and gentamicin. The obtained derivatives are non-toxic. Moreover, the obtained water-soluble polymers are highly efficient green catalysts for the aldol reaction in green solvent water. The catalysts can be easily extracted from the reaction mixture by its precipitation with green solvent ethanol followed by centrifugation and they can be reused at least 10 times. © 2021 Elsevier Lt