Depth distribution of light ions under grazing incidence on a target

The depth distribution of light ions under grazing incidence on the surface of a semi-infinite layer was analytically derived. It was assumed that the interaction between the ions and atoms of the medium is described by potentials in the form of an inverse power function: (V(r)～r ^?1/ν). Calculations showed that the ion distribution (ion density) peaks at some depth, rather than being a monotonic function. The more slowly the potential decreases (the larger the value of ν), the more distinct the ion density peak and the deeper its position. At large depths, the ion density drops according to a power law.     

Low-coherence enhanced backscattering from highly forward scattering media

We present a theoretical basis for calculation of the angular profile of the coherent backscattering intensity under low spatial coherence illumination. We take into account two contributions to the intensity, namely, the diffusion contribution and the contribution from the waves that experience the small-angle multiple scattering before and after single deflection in the backward direction. The latter contribution describes transport of light at subdiffusion length scales and is responsible for the wings of the backscattering angular profile. Our results are in good agreement with data of Monte-Carlo simulations and experiment.     

Propagation of a light beam in an absorbing medium with large-scale inhomogeneities

A method of solving the radiative transfer equation is proposed; it enables one to take into account the influence of absorption on the angular and spatial distributions of radiation under conditions of sharply anisotropic multiple scattering. For phase functions that decrease with an increase in the scattering angle by the power law, the total flux attenuation and profiles of the angular and spatial distributions in a strongly absorbing medium are studied. The obtained analytical dependences exhibit a good agreement with results of numerical solution of the radiative transfer equation.     

The effect of inelastic loss on the development of interatomic collision cascades

A theory of interatomic collision cascades in an infinite medium subject to inelastic energy loss (ionization slowdown) of particles is developed. Emphasis is on the angular and energy distributions of primary ions and cascade atoms upon slowdown. Analysis is performed under the assumption that single scattering of the particles follows the hard ball law, and the electronic stopping power of the medium is determined by the Lindhard formula. It is shown that the inclusion of slowdown directly in solving the Boltzmann transport equation radically changes the angular and energy spectra of the ions and cascade atoms obtained when the slowdown is ignored. Moreover, slowdown is the factor responsible for the anisotropy of the angular distributions of low-energy primary ions and cascade atoms.     

Effects of nondiffusive wave propagation upon coherent backscattering by turbid media

The nondiffusive contribution to the coherent backscattering intensity is calculated for the media with relatively large particles (size a is greater than wavelength λ). The results are in good agreement with the experimental data at the wings of the angular spectrum of the coherent backscattering. The shape of the backscattering peak is analyzed for strongly absorbing media. The correlation function of the intensity fluctuations is calculated for the scattering by Brownian particles at relatively large time shifts.