Fermi-edge polaritons in Bragg multiple-quantum-well structures

The polariton propagation in one-dimensional photonic crystals and quasicrystals based on highly doped quantum-well structures has been theoretically studied. The superradiant and photonic crystal regimes have been considered and expressions for band gap edges for light waves in the Bragg structures have been obtained. The reflection and absorption spectra of such systems have been calculated and the so-called two-wave approximation to their study has been applied. The optical properties of the doped multiple-quantum-well structures are compared with those of undoped ones.     

Dark-bright mixing of interband transitions in symmetric semiconductor quantum dots

In photoluminescence spectra of symmetric [111] grown GaAs/AlGaAs quantum dots in longitudinal magnetic fields applied along the growth axis, we observe in addition to the expected bright states also nominally dark transitions for both charged and neutral excitons. We uncover a strongly nonmonotonic, sign-changing field dependence of the bright neutral exciton splitting resulting from the interplay between exchange and Zeeman effects. Our theory shows quantitatively that these surprising experimental results are due to magnetic-field-induced ±3/2 heavy-hole mixing, an inherent property of systems with C(3v) point-group symmetry.     

Interplay of charge exchange and projectile excitation in the stopping of swift heavy ions

The electronic energy loss of a dressed ion penetrating through matter is commonly considered as being synonymous with the sum of the excitation energies of the target and the projectile in atomic collisions undergone during the passage. We show that this is not justified in projectile-ionizing collisions and discuss some consequences. Received 23 October 2002 / Received in final form 1st December 2002 Published online 18 February 2003     

Filtration Combustion of Humid Fuels

A comparative study of the filtration combustion of two types of fuel in mixtures with an inert material at various degrees of humidity was performed. The fuels were activated birch charcoal and pinewood. It was demonstrated that the combustion of activated charcoal was only slightly affected by humidity. In the case of pinewood combustion, an increase in the fuel humidity caused substantial decreases in the gasification mass rate and temperature. The composition of the gaseous products was found to change only for mixtures containing a large amount of pinewood with a humidity of more than 35%. This can be accounted for by a change in the extent of pinewood pyrolysis.     

An integral equation for the average radiation intensity in a stochastically macroinhomogeneous

An integral equation for the average intensity is derived for a simplified model of a stochastic macroinhomogeneous medium in the form of a stochastic field of attenuation and scattering co-efficients. This equation can be solved by the Monte Carlo method. A simulation algorithm is developed, maximally approximating the well-known algorithm for a deterministic medium. As an example, the algorithm is used to calculate the flux of solar radiation transmitted through a cloud layer.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 103–107, September, 1977.The authors are indebted to G. A. Mikhailov for a discussion and valuable comments as well as to G. M. Krekov for general interest and consultation.     

g-Factor of heavy ions: a new access to the fine structure constant

A possibility for a determination of the fine structure constant in experiments on the bound-electron g-factor is examined. It is found that studying a specific difference of the g-factors of B- and H-like ions of the same spinless isotope in the Pb region to the currently accessible experimental accuracy of 7 x 10(-10) would lead to a determination of the fine structure constant to an accuracy which is better than that of the currently accepted value. Further improvements of the experimental and theoretical accuracy could provide a value of the fine structure constant which is several times more precise than the currently accepted one.     

Interaction of wide-spectrum electromagnetic pulses with materials containing a superstructure

The interaction of wide-spectrum electromagnetic pulses with materials containing a superstructure is considered. The effective equation is obtained, which has a form of classical one-dimensional sine-Gordon equation, perturbed by quantum transitions between minibands. Numerical solutions are presented, and a region is established, where transitions between minibands play a significant role in the electromagnetic pulse dynamics.     

Plasma oscillations in two-dimensional semiconductor superstructures in the presence of high-frequency electric field

The effect of a high-frequency field on plasma oscillations in two-dimensional electron gas with a superstructure was studied. A dispersion relationship ω(k) was derived in the case of high temperatures (Δ ≪ T, where Δ the conductivity miniband width and T is the temperature in energy units). The calculations were based on the quantum theory of plasma oscillations in the casual-phase approximation while taking into account the umklapp processes.