Chelating Sorbents in Inorganic Chemical Analysis

This review is concerned with the preparation, characterization and the applications of new chelating sorbents in the separation, concentration and determination of trace metals from different complex samples

Chelating Sorbents in Inorganic Chemical Analysis

This review is concerned with the preparation, characterization and the applications of new chelating sorbents in the separation, concentration and determination of trace metals from different complex samples

Voltammetry of Aniline with Different Electrodes and Electrolytes

The aim of the present paper is the electrochemical characterization of aniline as well as obtaining of thin polyaniline films on carbon electrodes, which can be used as analytical sensors. The study was carried out by voltammetry in aqueuos medium within the potential range of -0.3 ↔ +1.4 V/S.C.E., at a scanning rate of 50 mV s-1, by using different electrode surfaces (Pt.E., P.C.E., Sp.C.E. and G.C.E.) and support electrolytes (H2SO4, H2SO4 + NaClO4, Na2SO4, Na2SO4 + NaClO4). Particular attention was paid to the aniline electropolymerization in neutral medium, in a low concentration (5 ⋅ 10-4 M), which was compared with that in acid medium. Voltammetric characteristics of aniline (Ea, (Ec, (ia, (ic) were estimated, the reversibility of electrode processes (ΔE(a-c), Sa/Sc ratio) was appreciated and the electropolymerization mechanism was correlated with the shapes of the voltammograms thus obtained. The electropolymerization efficiency was also estimated

Finite element 3-D model of a double quantum ring: effects of electric and laser fields on the interband transition

In this work, the changes in the energy of electrons and holes, oscillator strength and interband transition time when external fields are applied to a GaAs/AlGaAs semiconductor double ring grown by the droplet epitaxy technique are theoretically analyzed. We consider a static electric field and an intense laser field nonresonant with the quantum structure, with variable intensities and orientations with respect to the symmetry axis of the quantum ring. In the formalism of the effective mass approximation for electrons and holes, the energies and wavefunctions were numerically computed using the finite element method implemented with an accurate three-dimensional model of the real quantum ring. Laser dressing of the confining potential was performed using the exact integration formula at each point. Our results show major differences between the effects of the two types of applied fields, caused mainly by the static electric-field-induced strong polarizability of the confined electron-hole pair. In addition, the effects of both fields exhibit strong anisotropy in the electronic properties as a result of the particular flattened geometry of the quantum ring. Proper combinations of field strengths and orientations are helpful in designing accurate tools for the sensitive manipulation of interband radiative properties.Comment: 23 pages, 15 figures, 3 table

Electromagnetically induced transparency in double quantum dot under intense laser and magnetic fields: from

We theoretically investigated the effects of non-resonant intense laser and magnetic fields on the optical properties of asymmetric GaAs/AlGaAs double quantum dot related to the occurrence of electromagnetically induced transparency, using compact density-matrix formalism and effective mass approximation. The chosen structure has the advantage to present x-lambda(Λ)-configuration or y-ladder(Ξ)-configuration for EIT occurrence, depending on lasers polarization, at low values of the non-resonant laser, and to change the configuration from Λ to Ξ at the increase of the x-polarized non-resonant laser intensity. We discussed in detail the influences of the control laser field intensity, non-resonant laser strength and polarization, and magnetic field intensity on the absorption coefficient, refraction index and group index. It is found that: (i) the control laser or the non-resonant laser at the same control laser intensity influences more the system being in x-Ξ-configuration than in x-Λ-configuration and have intermediate effects on y-Ξ-configuration; (ii) the magnetic field has the greatest influence on the system being in x-Λ-configuration and the lowest for y-Ξ-configuration; (iii) the increment of the non-resonant intense laser or magnetic fields induces a red-shift of the transparency windows and sub (super) luminal frequency intervals for the Λ-configuration but a blue-shift for both Ξ-configurations

Aşezarea din secolele III-IV e.n. de la Timişoara-Cioreni / Eine Ansiedlung aus dem 3.-4. Jh.u.Z. bei Timişoara-„Cioreni”

Bejan Adrian, Benea Doina. Aşezarea din secolele III-IV e.n. de la Timişoara-Cioreni / Eine Ansiedlung aus dem 3.-4. Jh.u.Z. bei Timişoara-„Cioreni”. In: Materiale şi cercetări arheologice, N°15 1983. A XV-A sesiune anuală de rapoarte, Muzeul jedeţean Braşov – 1981. pp. 381-383

Şantierul arheologic Hodoni-Pustă / Die Ausgrabungen von Hodoni-Pustă

Bejan Adrian, Benea Doina. Şantierul arheologic Hodoni-Pustă / Die Ausgrabungen von Hodoni-Pustă. In: Materiale şi cercetări arheologice, N°15 1983. A XV-A sesiune anuală de rapoarte, Muzeul jedeţean Braşov – 1981. pp. 388-394

Intense laser effects on the optical properties of asymmetric GaAs double quantum dots under applied electric field

We investigated the combined effects of a non-resonant intense laser field and a static electric field on the electronic structure and the nonlinear optical properties (absorption, optical rectification) of a GaAs asymmetric double quantum dot under a strong probe field excitation. The calculations were performed within the compact density-matrix formalism under steady state conditions using the effective mass approximation. Our results show that: (i) the electronic structure and optical properties are sensitive to the dressed potential; (ii) under applied electric fields, an increase of the laser intensity induces a redshift of the optical absorption and rectification spectra; (iii) the augment of the electric field strength leads to a blueshift of the spectra; (iv) for high electric fields the optical spectra show a shoulder-like feature, related with the occurrence of an anti-crossing between the two first excited levels

Magnetic field controlled induced transparency by Autler–Townes splitting in pseudo-elliptic quantum ring

We theoretically investigated the effects of magnetic field and of the parameters of control and probe lasers on the transparency induced through Autler–Townes splitting (ATS) in GaAs/GaAlAs pseudo-elliptic quantum ring. We showed that if equal decay rates are considered the investigation of the electromagnetically induced transparency phenomenon can be done only in the strong coupling regime. Our study reveals that the quantum system is in a Λ configuration in the absence of external fields but, in the presence of the magnetic field, it may present simultaneously many configurations (of Λ, Ξ and V type) that allow the occurrence of transparency, separated by very narrow regions of magnetic fields where no configuration is active. The magnetic field determines almost periodically the switch between configurations. We demonstrated that in V (Ξ) configurations the ATS requires the greatest (lowest) intensity of the control laser and of the energy of the probe laser