Porous Silicon Photonic Crystal as a Substrate for High Efficiency Biosensing

Photonic crystals offer great possibilities for the improvement of performance of different kinds of devices. Due to the ability to control the light propagation and to change optical properties via interaction with the media photonic crystals have been widely used to increase the sensitivity of biosensing in many experimental setups. Among them some of the most interesting for practical applications are one-dimensional porous silicon photonic crystals. They could be easily fabricated, have big surface area, high sorption abilities, and have been shown to be able to change the emission of embedded luminophores. In this study we have fabricatedand performed the comprehensive investigation of the properties of hybrid system consisting of the porous silicon one-dimensional photonic crystals embedded with semiconductor quantum dots as the luminophores. We have demonstrated the ability of these systems to enhance the photoluminescence of luminophores and serve as the substrate for the high efficient biosensing. Keywords: Porous silicon, microcavity, quantum dots, luminescence enhancemen

Preparation of Freestanding Porous Silicon Photonic Crystals

Nowadays, the photonic crystals are of great interest and are widely used in photonics, biosensing, optoelectronics and other fields of research. The one-dimensional photonic crystals manufactured on the basis of porous silicon were proved to be the most suitable for applications due to their high sorption ability, large surface area, easiness of fabrication, and possibility to precisely control porosity and refractive index during electrochemical etching. However, the sensitivity of various kinds of gas and biological sensors as well as the performance of solar cells and other devices on the basis of porous silicon structures may be significantly increased by detaching the structures from the substrate. Here, we have developed and investigated the fabrication procedure of freestanding one-dimensional photonic crystals on the basis of porous silicon with the use of electropolishing method followed stabilization of freestanding porous silicon photonic structures through their oxidation. We have demonstrated that the developed and applied lift-off procedure does not violate the morphology and the photonic properties of the samples. Keywords: Porous silicon, photonic crystals, microcavity, thin films, freestanding photonic crystals

Modeling and Optimization of the Porous Silicon Photonic Structures

Photonic crystals and optical devices based on them are of great interest nowadays and are widely used in photonics, optoelectronics, and biosensing. One of the most practically using materials to fabricate one-dimensional photonic crystal is porous silicon due to the simple fabrication process, high porosity and ability to select precisely the refractive index by controlling the porosity. It has already been shown as the suitable material to be used as an element of many photonic devices including gas sensors and biosensors. However, because of the complicated porous structure, and silicon oxidation, occurring at the atmosphere conditions, optical properties of porous silicon photonic structures need to be stabilized by preventive oxidation. In order to predict eventual optical properties of fabricated photonic structures an adequate modeling should be performed. In our study we have developed a calculation model based on the combination of effective media approximations and transfer matrix method, which could precisely predict the reflection, transmission of the porous silicon photonic structures taking into account the dispersion of the refractive index of silicon and silicon oxide, and the oxidation degree. We also used numerical finite-difference time-domain calculations in order to investigate the luminescent properties of the lumiphores embedded into the porous photonic structure. Keywords: Porous silicon, microcavity, transfer matrix, effective media, FDT

Influence of the photon - neutrino processes on magnetar cooling

The photon-neutrino processes $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$, $\gamma \to \nu \bar \nu$ and $\gamma \gamma \to \nu \bar \nu$ are investigated in the presence of a strongly magnetized and dense electron-positron plasma. The amplitudes of the reactions $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$ and $\gamma \gamma \to \nu \bar \nu$ are obtained. In the case of a cold degenerate plasma contributions of the considering processes to neutrino emissivity are calculated. It is shown that contribution of the process $\gamma \gamma \to \nu \bar \nu$ to neutrino emissivity is supressed in comparision with the contributions of the processes $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$ and $\gamma \to \nu \bar \nu$. The constraint on the magnetic field strength in the magnetar outer crust is obtained.Comment: 8 pages, LaTeX, 2 PS figures, based on the talk presented by D.A. Rumyantsev at the XV International Seminar Quarks'2008, Sergiev Posad, Moscow Region, May 23-29, 2008, to appear in the Proceeding

Perspective directions in the development of architecture of the polytechnic museums

The museums of science and technology (or polytechnic) highlight the process of the innovational development of the society and have their own place in the system of school-science-industry-technical culture. The innovational activity of certain regions, states or groups of states is comprised of inventions, discoveries, new products and technologies that is all that provides the development of society and its competitive advantages. The modern polytechnic museums combine not only the functions of the demonstration of the achievements of the scientific and technological progress but also training and development of new inventions. In connection with the multifunctional nature of the modern polytechnic museum architects face the challenge of the creation of the architecture with universal dimensional planning elements, with its possible transformation in the course of time.Keywords: museum; science; innovations; technology; typolog