Radiochemical physics of the upper Earth’s atmosphere

The paper discusses the goals and tasks of the radiochemical physics and its possible applications. These include measurements of ocean salinity and soil moisture, control of the state of vegetation, and forecast of the weather and water balance of the Earth.     

Surface plasma oscillations in layer metal particles

Light scattering cross section and positions of two surface plasma resonances in a layer metal particle containing dielectric foreign nucleus are calculated within the random phase approximation. The results obtained provide a possible explanation of contradictions in size dependence of surface plasma resonance position [1, 2] and are able to explain two peak structure of photoabsorption cross section of small silver particle observed in [1].     

Proof-of-concept implementation of the massively parallel algorithm for simulation of dispersion-managed WDM optical fiber systems

We perform a proof-of-concept implementation of the massively parallel algorithm [P. M. Lushnikov, Opt. Lett. 27, 939 (2002)] for simulation of dispersion-managed wavelength-division-multiplexed optical fiber systems. Linear scalability of the algorithm with the number of computer cores is demonstrated. Exact result on the accuracy of the implemented algorithm is found analytically and confirmed numerically as well as it is compared with the accuracy of the standard split-step algorithm.     

Dispersion-managed soliton in a strong dispersion map limit

A dispersion-managed optical system with stepwise periodic variation of dispersion is studied in a strong dispersion map limit in the framework of the path-averaged Gabitov-Turitsyn equation. The soliton solution is obtained by analytical and numerical iteration of the path-averaged equation. An efficient numerical algorithm for finding a DM soliton shape is developed. The envelope of soliton oscillating tails is found to decay exponentially in time, and the oscillations are described by a quadratic law.     

Dynamics of cubic-tetragonal phase transition in KNbO<Subscript>3</Subscript> perovskite

The low-energy part of the vibration spectrum of KNbO₃ was studied by cold neutron inelastic scattering in the cubic phase. In addition to acoustic phonons, we observe strong diffuse scattering, which consists of two components. The first one is quasistatic and has a temperature-independent intensity. The second component appears as quasielastic scattering in the neutron spectrum, indicating a dynamic origin. From analysis of the inelastic data, we conclude that the quasielastic component and the acoustic phonon are mutually coupled. The susceptibility associated with the quasielastic component grows as the temperature approaches T _C .     

<Emphasis Type="Italic">E-T</Emphasis> phase diagram of lead magnesium niobate relaxor ferroelectric in the Mandelstam-Brillouin scattering spectra

The results of studying the velocity of hypersonic longitudinal acoustic phonons over a wide temperature range under an applied constant electric field in the PbMg_1/3Nb_2/3O₃ (PMN) relaxor ferroelectric are reported. An analysis of the experimental data on the basis of the existing E-T phase diagrams shows the necessity of a substantial change in the current concepts. Two radically different states—with the reversible and irreversible behavior of velocity—have been observed experimentally in the induced ferroelectric phase. A modified _E-T phase diagram of the PMN crystal is suggested.     

Vibrational density of states of hen egg white lysozyme

The resonant Raman scattering in GeSi/Si structures with GeSi quantum dots has been analyzed. These structures were formed at various temperatures in the process of molecular-beam epitaxy. It has been shown that Raman scattering spectra recorded near resonances with the E₀ and E₁ electronic transitions exhibit the lines of Ge optical phonons whose frequencies differ significantly from the corresponding values in bulk germanium. In the structures grown at low temperatures (300–400°C), the phonon frequency decreases with increasing excitation energy. This behavior is attributed to Raman scattering, which is sensitive to the size of quantum dots, and shows that quantum dots are inhomogeneous in size. In the structures grown at a higher temperature (500°C), the opposite dependence of the frequency of Ge phonons on excitation energy is observed. This behavior is attributed to the competitive effect of internal mechanical stresses in quantum dots, the localization of optical photons, and the mixing of Ge and Si atoms in structures with a bimodal size distribution of quantum dots.