Optical pumping of the electron spin polarization in bulk CuCl

In CuCl bulk crystal negatively charged excitons (trions $X^-$) can be induced by the resonant optical excitation of extra electrons in conduction band minimum. In the case of light polarization and due to the top valence band structure of CuCl only the electrons with spin antiparallel to the direction of the light propagation contribute to the formation of $X^-$, while the emerging $X^-$ can recombine into both possible electron states, with spin parallel and antiparallel to the direction of light propagation. We propose to use this mechanism for optical electronic spin pumping. We describe the dynamics of pumping in terms of density matrix formalism. The coherent pumping laser pulse propagating through the sample is described by Maxwell wave equation coupled to the density matrix evolution equations. The results of our approximate simple model calculations suggest that spin polarization close to 100% can be achieved in time shorter than 100ps.Comment: new extended version, 7 pages, 4 figure

The anatomy of the tympanic sinus

The tympanic sinus is one of the most important structures of the human temporal bone. Located in its vicinity are the round window, posterior semicircular canal and facial nerve. The study was performed on 30 temporal bones taken from adult cadavers of both sexes. After the tympanic sinus had been identified, its morphological features were evaluated. The sinus was then measured using a graticule with an accuracy of 0.05 mm. Also measured were the shortest distances from the tympanic sinus to the neighbouring structures (the lateral and posterior semicircular canal, the facial nerve canal and the jugular fossa). The measurements were performed under a surgical microscope with eye-piece graduation of 0.05 mm accuracy. Four main morphological types of fossa of the tympanic sinus and two main developmental forms, a deep sinus and a shallow sinus, were distinguished. The existence of a deep sinus was associated with absence of the bridge and the sinus was shallower when the bridge was prominent. The very deep sinuses were located close to the facial canal, in some cases penetrating deep in its vicinity (in some cases even going beyond two thirds of the canal’s circumference), which poses a real risk of facial nerve damage during surgical removal of a lesion located in close proximity to the nerve. In most cases the tympanic sinus is elliptical in shape and its long diameter lies in the vertical plane (mean value: 2.73 × 2.23 mm). The mean distances from the tympanic sinus to the facial nerve canal, lateral semicircular canal, posterior semicircular canal and jugular fossa were 1.5 mm, 2.1 mm, 1.59 mm and 5.5 mm respectively. No correlation was observed between the measurement results and either sex or side

The Radiative Biexciton-exciton Recombination in Wurtzite Crystals

In the effective mass approximation in the two-band model of semiconductor the dipole moment matrix element due to the biexciton-exciton transition is expressed by the functional of the exciton and biexciton envelopes. In comparison to previous estimations of the biexciton-exciton transition probability the detailed band structure at band extrema was taken into account and the biexciton envelope optimized by variational calculation was used in calculations. The oscillator strength ratio I$\text{}^{2}$=f$\text{}_{biex-ex}$/f$\text{}_{band-to-band}$ is given for several values of σ=m$\text{}_{e}$/m$\text{}_{h}$. The calculated functional I for CdS is about four times smaller compared to that obtained by Hanamura. The calculated giant oscillator strength of the biexciton-exciton recombination in CdS is f$\text{}_{biex-ex}$=4×10$\text{}^{2}$

Excitonic Molecule in CuCl Crystal

The electronic structure of a biexciton is discussed while taking into account the detailed band structure of CuCl. The fine structure of the excitonic molecule is clarified with the effective electron-hole exchange effect taken into account beyond the effective mass approximation. The electron-hole exchange interaction mixes the states of opposite parities with respect to the permutation of electrons and holes. Two trial envelope functions, symmetric and antisymmetric under the permutation of two electrons or two holes, were used in the numerical minimization of the ground state energy of the biexciton. The obtained binding energy of the biexciton, as well as, the ratio of the mixing of the trial envelope functions of opposite parities are presented

The Nonlinear Absorption Coefficient for Direct Two-Photon Creation of Biexciton

The absorption coefficient for the two-photon creation of biexciton is calculated for CuCl and wurtzite crystals. Because of the resonance effect only the intermediate lowest optically active excitonic states are taken into account. The absorption coefficient is expressed by a functional of the biexciton envelope. The numerical results are computed with the envelope function of Hylleraas-Ore type (modified and minimized by Brinkman et al). The obtained results for CuCl are in good agreement with absorption measurements published by Gale and Mysyrowicz

Protection of Payment Card Users with Relation to Innovative Security Systems

The article recounts the ongoing changes with regard to the legal definition of payment cards, alterations procured by the entrance into force of an amendment to the Payment Cards Act, dated 12 July 2013. Furthermore, the article expounds the principles of liability in connection with unauthorized transactions that are aimed at protecting the users of payment cards. The legislative direction adopted by the Polish lawmakers is in line with Directive 2007/64/EC pertaining to payment services within an internal market, which sets out to establish a framework for protecting funds accumulated on the clients’ accounts. Various innovative security systems being implemented on the payment card market are referred to in the last part of the article. It is submitted that the introduction of biometric and nanotechnology solutions in automatic identity verification processes may eventually lead to the elimination of payment cards in their physical form. However, these innovative solutions carry various risks. The underlying issue is associated with potentially unlawful breach of the constitutional right to privacy in cases where the identity of a person is verified automatically. For this reason, it is important to establish whether biometric data or nanoparticles containing information on payment card holders constitute personal data within the meaning of the Personal Data Act. Such analysis should include how both systems conduct the automatic personal identification process and the manner in which the personal data is gathered, processed and stored

The Nonlinear Absorption Coefficient for Direct Two-Photon Creation of Biexciton

The absorption coefficient for the two-photon creation of biexciton is calculated for CuCl and wurtzite crystals. Because of the resonance effect only the intermediate lowest optically active excitonic states are taken into account. The absorption coefficient is expressed by a functional of the biexciton envelope. The numerical results are computed with the envelope function of Hylleraas-Ore type (modified and minimized by Brinkman et al). The obtained results for CuCl are in good agreement with absorption measurements published by Gale and Mysyrowicz

New thick film composites of lower sintering temperature for ohimic contacts for sollar cells

W pracy przedstawiono nowa generację materiałów grubowarstwowych przeznaczonych do nanoszenia sitodrukiem, w których fazę przewodzącą stanowią proszki srebra o submikronowej wielkości ziaren. Zaletą tych past jest to, że nie zawierają fazy szkliwa, które wspomagało proces spiekania, a jednocześnie pogarszało przewodnictwo elektryczne warstwy. Kolejna zaleta tych past to możliwość spiekania w niższych temperaturach, co zwiększa obszar stosowania tych past w różnych procesach technologicznych.New generation of screen printed thick film materials where conducting phase was of submicron silver powder. The main advantage of these pastes compare with the standard ones is that they do not contain glassy phase. This phase helped sintering process, but caused the worse electrical conductivity. Another advantage of this paste is the lower sintering temperature which enables its application in much wider range of technological processes