Nonlinear interaction of the elliptically polarized light with CdSxSe₁₋x quantum dots

Peculiarities of the influence of ruby laser elliptically polarized light on the absorption saturation in glass with CdSxSe₁₋x nanocrystals and absorption saturation on light polarization were investigated. It was established that the change of ellipticity from zero to unity does not influence the dependence of transmission on the light intensity. Within the range of linear optics ( I₀<I*₁, where I₀ is the intensity of pumping,I₁ – bleaching threshold) or within the range of absorption saturation ( I₀>I*₂, where I*₂ is the absorption saturation threshold), light polarization at the entrance to glass with CdSxSe₁₋x nanocrystals is congruent to light polarization at the exit from glass. Within the range of a nonlinear dependence of absorption on the light intensity (I*₁< I₀<I*₂ ) , deformation of polarization ellipse increases, when nanocrystals for which C ⊥ E are bleached, but for nanocrystals where E || C are not bleached this deformation has a maximum value

Temperature effect on light polarization in uniaxial crystals

It has been shown that changes in temperature of uniaxial single crystal are accompanied by changes in the polarization plane angular position and the light intensity that subsequently passes through the polarizer, uniaxial crystal, and analyzer. These effects introduce systematic errors in the results of researching the nonlinear processes. To minimize this harmful effect, polarization researches must be carried out at a constant sample temperature. For example, research of the nonlinear polarization processes in CdS should be done with a sample temperature uncertainty no higher than ±1 K

Influence of absorption saturation on the shape of CdSe absorption edge

Influence of light polarization on absorption saturation for wurtzite modification CdSe has been investigated. It has been ascertained that the size of blurring the fundamental absorption edge for wurtzite modification CdSe is determined by the non-equilibrium electron filling both the conduction band extremum, when the energy of photons h is higher than the bandgap energy Eg, and the density-ofstate tail caused by the presence of static disorder, when the hν < Eg. The density-of-state tail resulting from the presence of dynamic disorder is not filled with electrons because of continuous changes of the dynamic potential relief value in time. In the high-energy spectral region, change in the absorption coefficient is limited by the stimulated emission processes

Analysis of the silicon solar cells efficiency. Type of doping and level optimization

The theoretical analysis of photovoltaic conversion efficiency of highly effective silicon solar cells (SC) has been performed for n-type and p-type bases. Considered here is the case when the Shockley–Read–Hall recombination in the silicon bulk is determined by the deep level of Fe. It has shown that, due to asymmetry of recombination parameters inherent to this level, the photovoltaic conversion efficiency is increased in SC with the n-type base and decreased in SC with the p-type base with the increase in doping. Two approximations for the band-to-band Auger recombination lifetime dependence on the base doping level are considered when performing the analysis. The experimental results are presented for the key characteristics of SC based on a-Si:H–n-Si heterojunctions with intrinsic thin layer (HIT). A comparison between the experimental and calculated values of the HIT cell characteristics has been made. The surface recombination velocity and series resistance are determined from it with a complete coincidence of the experimental and calculated SC parameters’ values. Apart from the key characteristics of SC, surface recombination rate and series resistance were determined from the results of this comparison, in full agreement with the experimental findings

Fast six-channel pyrometer for warm-dense-matter experiments with intense heavy-ion beams

This paper describes a fast multi-channel radiation pyrometer that was developed for warmdense-matter experiments with intense heavy ion beams at Gesellschaft fur Schwerionenforschung mbH (GSI). The pyrometer is capable of measuring of brightness temperatures from 2000 K to 50000 K, at 6 wavelengths in visible and near-infrared parts of spectrum, with 5 nanosecond temporal resolution and several micrometers spatial resolution. The pyrometer's spectral discrimination technique is based on interference filters, which act as filters and mirrors to allow for simultaneous spectral discrimination of the same ray at multiple wavelengths

An integrable discretization of the rational su(2) Gaudin model and related systems

The first part of the present paper is devoted to a systematic construction of continuous-time finite-dimensional integrable systems arising from the rational su(2) Gaudin model through certain contraction procedures. In the second part, we derive an explicit integrable Poisson map discretizing a particular Hamiltonian flow of the rational su(2) Gaudin model. Then, the contraction procedures enable us to construct explicit integrable discretizations of the continuous systems derived in the first part of the paper.Comment: 26 pages, 5 figure

Non-isothermal physical and chemical processes in superfluid helium

Metal atoms and small clusters introduced into superfluid helium (He II) concentrate there in quantized vortices to form (by further coagulation) the thin nanowires. The nanowires’ thickness and structure are well predicted by a double-staged mechanism. On the first stage the coagulation of cold particles in the vortex cores leads to melting of their fusion product, which acquires a spherical shape due to surface tension. Then (second stage) provided these particles reach a certain size they do not possess sufficient energy to melt and eventually coalesce into the nano-wires. Nevertheless the assumption of melting for such refractory metal as tungsten, especially in He II, which possesses an extremely high thermal conductivity, induces natural skepticism. That is why we decided to register directly the visible thermal emission accompanying metals coagulation in He II. The brightness temperatures of this radiation for the tungsten, molybdenum, and platinum coagulation were found to be noticeably higher than even the metals’ melting temperatures. The region of He II that contained suspended metal particles expanded with the velocity of 50 m/s, being close to the Landau velocity, but coagulation took place even more quickly, so that the whole process of nanowire growth is completed at distances about 1.5 mm from the place of metal injection into He II. High rate of coagulation of guest metal particles as well as huge local overheating are associated with them concentrating in quantized vortex cores. The same process should take place not only for metals but for any atoms, molecules and small clusters embedded into He II

Non-isothermal physical and chemical processes in superfluid helium

Metal atoms and small clusters introduced into superfluid helium (He II) concentrate there in quantized vortices to form (by further coagulation) the thin nanowires. The nanowires’ thickness and structure are well predicted by a double-staged mechanism. On the first stage the coagulation of cold particles in the vortex cores leads to melting of their fusion product, which acquires a spherical shape due to surface tension. Then (second stage) provided these particles reach a certain size they do not possess sufficient energy to melt and eventually coalesce into the nano-wires. Nevertheless the assumption of melting for such refractory metal as tungsten, especially in He II, which possesses an extremely high thermal conductivity, induces natural skepticism. That is why we decided to register directly the visible thermal emission accompanying metals coagulation in He II. The brightness temperatures of this radiation for the tungsten, molybdenum, and platinum coagulation were found to be noticeably higher than even the metals’ melting temperatures. The region of He II that contained suspended metal particles expanded with the velocity of 50 m/s, being close to the Landau velocity, but coagulation took place even more quickly, so that the whole process of nanowire growth is completed at distances about 1.5 mm from the place of metal injection into He II. High rate of coagulation of guest metal particles as well as huge local overheating are associated with them concentrating in quantized vortex cores. The same process should take place not only for metals but for any atoms, molecules and small clusters embedded into He II