Yoshi-Hiko Ohtsuki

Kikuchi Patterns and Inelastic Scattering

Numerical calculations are performed for contribution of various kinds of inelastic scattering, valence electron excitations (including the plasmon excitation), core electron excitations and phonon excitations on Kikuchi pattern of Si single crystal. An explanation of defect Kikuchi band is proposed by considering inelastic scatterings in detail. Two negative circle regions on the Kikuchi band are found theoretically. Experimental results corresponding to these calculations are also presented.

Complex Continuum Potential for Channeling

Complex continuum potentials for channeling due to non-local inelastic scatterings are introduced. The relation between the complex continuum potential and the Yoshioka term for electron diffraction is studied. For an example, phonon excitations are considered in detail for numerical calculations of the imaginary continuum potential (absorption coefficient). The local diffusion constant for dechanneling theory is also discussed.

Normal and Abnormal Absorption Coefficients of X-Rays

The normal and the abnormal absorption coefficients of X-rays due to the Compton scattering and the thermal diffuse scattering (TDS) are calculated numerically by taking into account the temperature effect. It is found that effects of both scatterings are comparable for light atoms such as Al and Si, and that the effect of the latter is larger than the former for heavier atoms.

The Correction of the Mean Inner Potential in Electron Diffraction

The corrections of the mean inner potential, or the scattering factor of 0-th order V 0 due to plasmon excitation and phonon excitation are calculated on the basis of the 2nd order perturbation theory. It is shown that the contribution of the plasmon excitation becomes large in low energy electron diffraction. Numerical calculations are performed for Si and Al.

Theory of Low Energy Electron Diffraction. III. Inelastic Scattering

The theory for inelastic scattering in low energy electron diffraction is developed. The effects of diffraction of low energy electron beam on the inelastic scattering are predicted. The diffraction enhances or diminishes the usual intensity of inelastically-scattered electron beam from the crystal surface. The effects of surface-phonon excitations and surface-plasmon excitations are considered in detail.

Exchange Effects on Kikuchi Band and Abnormal Absorption in Electron Diffraction

The abnormal absorption coefficient and the Kikuchi band by the core electron excitations are calculated in detail for Si and Al by considering the exchange effect in the inelastic scattering factor S ( q h , q ). It is shown that the exchange term plays an important role in the calculation, and that the abnormal absorption coeffcient becomes negative for higher indexes. The negative region of the Kikuchi band is enlarged by the exchange terms. The calculated abnormal absorption coefficients for Si and Al are very small compared with results of Radi and Whelan.

ABNORMAL STOPPING POWER OF PROTON AND ION CHANNELING.

A method to calculate the “abnormal” stopping power of the planar channeled particle in crystal is proposed. Making use of the formula and Bohrs classical model the abnormal stopping power is calculated as a function of the distance from the channeling wall for electronic and nuclear excitations.

Measurements of Ratio of Abnomal to Normal Absorption Coefficients for Electrons in Crystal from Pseudo-Kikuchi Patterns

The intensity profiles of pseudo-Kikuchi bands in the scanning electron microscope are obtained theoretically as a function of W using the two beam dynamical theory of electron diffraction; where W is a deviation parameter from the exact Bragg condition. According to the theory, the ratio of the abnormal to normal absorption coefficients Δ µ g /µ 0 can be determined from two different parameters of the experiment; a ratio R of the maximum to minimum intensities or W values at the positions of the maximum and minimum intensities near the Kikuchi band edge in the intensity profiles across the band. The comparison between the theory and experiment is examined for the (220) pseudo-Kikuchi bands in Si. The values Δ µ g /µ 0 obtained from R and W values are 0.10±0.03 and 0.20±0.05, respectively. The value obtained from W s in this experiment agrees approximately with one quoted by Meyer-Ehmsen. However the value obtained from R is smaller than those of others. This fact is caused by the effect of inelastically...

Effects of Bremsstrahlung on the Linear Absorption Coefficient for Relativistic Electron Diffraction

The effect of the inelastic scattering by Bremsstrahlung is calculated between 10 KeV and 2000 KeV of the energy of the incident beam. The absolute value and the β(= v / c )-dependence of µ 0 -1 is evaluated numerically, and it is shown that the effect considered here is much small as compared with one of the electronic excitation.

Impurity Effects on the Plasma Oscillation of an Electron Gas

The one-particle Greens function for a system of degenerate non- interacting electrons is used to calculate the longitudinal dielectric constant of the electron system. The imaginary part of the dielectric constant is used to determine the dispersive term of the damping factor, which factor governs the plasma oscillations in the electron system.