Structure and Morphology Effects on the Optical Properties of Bimetallic Nanoparticle Films Laser Deposited on a Glass Substrate

International audienceMoving nanosecond laser system is used for laser-assisted thermodiffusion deposition of metallic nanoparticles from water-based colloidal solutions. The results obtained for both gold and silver nanoparticles show that film morphology strongly depends on laser scanning speed and the number of passages. We show, furthermore, the possibility of producing bimetallic Au:Ag thin films by laser irradiation of the mixed solutions. As a result of several laser scans, granular nanometric films are found to grow with a well-controlled composition, thickness, and morphology. By changing laser scanning parameters, film morphology can be varied from island structures to quasi-periodic arrays. The optical properties of the deposited structures are found to depend on the film composition, thickness, and mean separation between the particles. The transparency spectra of the deposited films are shown to be defined by their morphology

Thermal stability of internal gettering of iron in silicon and its impact on optimization of gettering

The redissolution behavior of gettered iron was studied in p-type Czochralski-grown silicon with a doping level of 2.5×10exp14 cm−3 and an oxide precipitate density of 5×10exp9 cm−3. The concentrations of interstitial iron and iron–boron pairs were measured by deep level transient spectroscopy. It was found that the dependence of redissolved iron concentration on annealing time can be fitted by the function C(t)=C_0[1−exp(−t/tau_diss)], and the dissolution rate tau−1diss has an Arrhenius-type temperature dependence of tau−1diss=4.01×10exp4 × exp[−(1.47±0.10) eV/k_BT] s−1. Based on this empirical equation, we predict how stable the gettered iron is during different annealing sequences and discuss implications for optimization of internal gettering.Peer reviewe

Structure and Morphology Effects on the Optical Properties of Bimetallic Nanoparticle Films Laser Deposited on a Glass Substrate

Moving nanosecond laser system is used for laser-assisted thermodiffusion deposition of metallic nanoparticles from water-based colloidal solutions. The results obtained for both gold and silver nanoparticles show that film morphology strongly depends on laser scanning speed and the number of passages. We show, furthermore, the possibility of producing bimetallic Au:Ag thin films by laser irradiation of the mixed solutions. As a result of several laser scans, granular nanometric films are found to grow with a well-controlled composition, thickness, and morphology. By changing laser scanning parameters, film morphology can be varied from island structures to quasi-periodic arrays. The optical properties of the deposited structures are found to depend on the film composition, thickness, and mean separation between the particles. The transparency spectra of the deposited films are shown to be defined by their morphology

Distinction between the Poole-Frenkel and tunneling models of electric field-stimulated carrier emission from deep levels in semiconductors

The enhancement of the emission rate of charge carriers from deep-level defects in electric field is routinely used to determine the charge state of the defects. However, only a limited number of defects can be satisfactorily described by the Poole-Frenkel theory. An electric field dependence different from that expected from the Poole-Frenkel theory has been repeatedly reported in the literature, and no unambiguous identification of the charge state of the defect could be made. In this article, the electric field dependencies of emission of carriers from DX centers in AlxGa1-xAs:Te, Cu pairs in silicon, and Ge:Hg have been studied applying static and terahertz electric fields, and analyzed by using the models of Poole-Frenkel and phonon assisted tunneling. It is shown that phonon assisted tunneling and Poole-Frenkel emission are two competitive mechanisms of enhancement of emission of carriers, and their relative contribution is determined by the charge state of the defect and by the electric-field strength. At high-electric field strengths carrier emission is dominated by tunneling independently of the charge state of the impurity. For neutral impurities, where Poole-Frenkel lowering of the emission barrier does not occur, the phonon assisted tunneling model describes well the experimental data also in the low-field region. For charged impurities the transition from phonon assisted tunneling at high fields to Poole-Frenkel effect at low fields can be traced back. It is suggested that the Poole-Frenkel and tunneling models can be distinguished by plotting logarithm of the emission rate against the square root or against the square of the electric field, respectively. This analysis enables one to unambiguously determine the charge state of a deep-level defect

МАТЕМАТИЧЕСКОЕ МОДЕЛИРОВАНИЕ УПРАВЛЕНИЯ ПЕРЕГРУЗОЧНЫМИ ПРОЦЕССАМИ В МОРСКОМ ПОРТУ

Transport nodes play central role in freight traffic. In spite of construction of new Russian port transshipment facilities the demand for them isn’t satisfied (for instance in international trade only 70% of demandis met). Thereupon thereis a need toincrease the efficiency of transport nodes particularly by optimization of management of transshipment and port facilities on the basis of modern information and computer technology.Для решения задач управления перегрузочными процессами разработана граф-модель и её аналог – матричная модель, которые позволяют с разных сторон взглянуть на проблемы оптимизации грузовой работы в морском транспортном узле. В статье представлены результаты моделирования, помогающие оценить затраты на производство, а также оптимизировать условия перегрузки грузов по экономическому критерию – суммарному комплексному расходу на перемещение грузопотока. Случайный характер процессов, протекающих в инфраструктурах транспортного узла, дает возможность интерпретировать строящиеся здесь управленческие модели как вероятностные и относить их к моделям массового обслуживания

СЫПУЧИЕ ГРУЗЫ В ПОРТУ: ОБРАБОТКА ПО СИТУАЦИИ

The article describes study on approaches towards solution of a problem of situational control of transshipment of goods at the sea port on the basis of virtual technology and mathematical simulation. The results of the study are demonstrated with the help of examples of Murmansk sea port and Internet-site, which serves to prove the efficiency of electronic data exchange.Сформированы подходы к решению задач ситуационного управления на основе методов виртуальных технологий и математического моделирования. Показана их реализация на материалах Мурманского морского порта и интернет-сайта, с помощью которого демонстрируется эффективность электронного обмена данными

Traditional Method in Training Architect (on the Example of a Technical University)

Construction and architectural education focuses on the formation of a socially and professionally active person with high competence, flexibility and creativity. It is important to maintain those teaching methods that contribute to obtaining the desired result in the educational process of vocational training, especially in a technical university. The importance of traditional teaching methods in the training of professional architects remains relevant from the time of the opening of the VHUTEMAS and BAUHAUS schools to the present day. The sequence of implementation of coursework projects by students of UrFU architects confirms this.Строительно-архитектурное образование ориентируется на становление социально и профессионально активной личности, обладающей высокой компетентностью, гибкостью и креативностью. Необходимо сохранить в учебном процессе, особенно в техническом вузе, те методы обучения, которые способствуют подготовке востребованных на рынке труда выпускников. Важность традиционных методов обучения в подготовке архитекторов-профессионалов остается актуальной со времени открытия школ ВХУТЕМАС и БАУХАУС до нынешних дней. Последовательность выполнения курсовых проектов студентами-архитекторами УрФУ подтверждает это

Sustainable Urban Development (on the Example of a Student Competition)

Проект по благоустройству набережной реки Кыштымка преследовал цель создать архитектурное общественное и культурное пространство, которое бы реализовало благоустройство участка городской территории в контексте устойчивого развития.The project on the improvement of the Kyshtymka river embankment aimed at creating an architectural public and cultural space that would realize the improvement of the urban area in the context of sustainable development

Muon Spin Relaxation Study of (La, Ca)MnO3

We report predominantly zero field muon spin relaxation measurements in a series of Ca-doped LaMnO_3 compounds which includes the colossal magnetoresistive manganites. Our principal result is a systematic study of the spin-lattice relaxation rates 1/T_1 and magnetic order parameters in the series La_{1-x}Ca_xMnO_3, x = 0.0, 0.06, 0.18, 0.33, 0.67 and 1.0. In LaMnO_3 and CaMnO_3 we find very narrow critical regions near the Neel temperatures T_N and temperature independent 1/T_1 values above T_N. From the 1/T_1 in LaMnO_3 we derive an exchange integral J = 0.83 meV which is consistent with the mean field expression for T_N. All of the doped manganites except CaMnO_3 display anomalously slow, spatially inhomogeneous spin-lattice relaxation below their ordering temperatures. In the ferromagnetic (FM) insulating La_{0.82}Ca_{0.18}MnO_3 and ferromagnetic conducting La_{0.67}Ca_{0.33}MnO_3 systems we show that there exists a bi-modal distribution of \muSR rates \lambda_f and \lambda_s associated with relatively 'fast' and 'slow' Mn fluctuation rates, respectively. A physical picture is hypothesized for these FM phases in which the fast Mn rates are due to overdamped spin waves characteristic of a disordered FM, and the slower Mn relaxation rates derive from distinct, relatively insulating regions in the sample. Finally, likely muon sites are identified, and evidence for muon diffusion in these materials is discussed.Comment: 21 pages, 17 figure