Absorption of Radiation by ITO Semiconductor Nanoparticles in Plasmon Resonance Region

The radiation absorption cross section of indium–tin oxide (ITO) semiconductor nanoparticles of various sizes placed in various media is calculated in the region of plasmon resonance. The photoabsorption cross sections calculated within the framework of the Mie theory and in the dipole approximation are compared with each other and with the available experimental data. The limits of applicability of the dipole approximation are determined. The prospects of using these nanoparticles as an active material in optical plasmon sensors are assessed.     

Scattering of Electromagnetic Radiation by ITO Nanoparticles with Various Doping Levels

The process of scattering of radiation by indium?tin oxide (ITO) nanoparticles is theoretically studied at various degrees of doping and for different radii of nanoparticles. Qualitative conclusions are made about the character of the dependence of the scattering cross section on the frequency with variation of the particle size and the percentage content of tin. The prospects of using ITO nanoparticles as an active substance in optical sensors are estimated.     

Polarization-interference effects in the bremsstrahlung of quasiclassical electrons on ions with a core

The polarization dependence of the stimulated bremsstrahlung and inverse bremsstrahlung (SBIB) of quasiclassical electrons on highly charged ions with a core is calculated in the approximation of a specified Coulomb current. Emission frequencies close to an eigenfrequency of the ion core are considered. The contributions of the static and polarization channels are taken into account in the amplitude of the process. When the nondipole nature of the interaction between the incident particle and a resonant transition in the ion core is taken into account, interference between these channels causes the spectral-amplitude characteristics of the process to assume a specific dependence on the angle α between the electric field intensity vector of the electromagnetic wave and the initial velocity vector of the incident particle. This dependence, which persists after integration of the cross section over the scattering angle of the incident particle, causes interference effects, viz., asymmetry of the line shape and dips in the dependence of the SBIB cross section on electric field intensity, to appear for α=π/2 and significantly reduces them for α=0. Zh. éksp. Teor. Fiz. 115, 1619–1629 (May 1999)     

Absorption of ultrashort electromagnetic pulses in plasma with inhomogeneous distribution of density and temperature

The analysis of influence of the inhomogeneous distribution of temperature and density of atoms on the probability of absorption of ultrashort electromagnetic pulses in plasma is carried out. A specific example of divertor plasma of tokamaks and absorption in the Lyman series (at the Ly-α line) is considered. It is shown that the absorption probability may exceed relative populations of excited levels in divertor plasma by several orders of magnitude. The influence of the pulse duration on the probability of excitation of an atomic level is considered. The results suggest a possibility of a sharp increase in a fluorescence signal under the action of an ultrashort pulse.     

Modification of the EDXD method for diagnostics of polycrystalline and fine-grained media

The possibilities of using broadband X rays for diagnostics of the atomic structure of solids are considered. It is proposed to use virtual photons of the Coulomb field of a relativistic electron beam as primary probe radiation.     

Polarization Bremsstrahlung radiation on a nanosphere in a dielectric

Within the limits of a new approach based on the Mie scattering theory, polarization bremsstrahlung radiation (PBR), arising during electron scattering on a metallic nanosphere with radius from 10 to 100 nm placed in a dielectric medium is theoretically investigated. The spectral range close to the plasmon resonance is considered, where the contribution of the polarized channel to bremsstrahlung radiation dominates. Spectral, velocity, and angular PBR characteristics are calculated. The sensitivity of the PBR spectrum to the dielectric permittivity of the medium surrounding the nanosphere is demonstrated.     

Conformational, optical, and electrooptical properties of cellulose pelargonates in solutions

Newly prepared cellulose pelargonate samples of various molecular weights were studied in dioxane and chloroform solutions by isothermal translation diffusion, high-speed sedimentation, flow birefringence (Maxwell effect), electric birefringence (Kerr effect), and viscometry. The conformational, hydrodynamic, optical, electrooptical, and dynamic characteristics of the polymer were determined.     

Hydrodynamic and conformational properties of cellulose valerate molecules in dilute solution

Using the methods of molecular hydrodynamics, structural-conformational studies have been performed for a number of cellulose valerate and acetovalerate samples in the molecular-mass range M = (58.1–464.3) × 10³ and with a mean degree of substitution of 182.4 with respect to valeric acid isomers. The conformations of valerate-substituted cellulose molecules are characterized by an increased local packing density of monomer units. The molecular conformations are quantitatively described in terms of the helix formed by the succession of vectors connecting glycoside oxygens of a chain. The molecular-hydrodynamic and conformational characteristics of cellulose valerate are compared with the corresponding characteristics of cellulose myristate.