Diffusion multiple d'électrons par un milieu atomique amorphe

Abstract

Abstract Multiple electronic scattering in solids Recent developments in the techniques of physical analysis using probes require a better knowledge of how particles travel in matter. If the problem of simple interactions is well known, that of multiple interactions involves numerical methods such as simulating trajectories of particles in a target using Monte Carlo methods, or solving Boltzmann's transport equation. In spite of the powerful means of calculation now available, an analytical solution to the problem of the propagation of a monoenergetic beam of electrons in a target should have the following advantages : it should bring out the relative importance of the parameters defining the different interactions; it should lead to numcrical values that can be worked out with a small calculator; it should be simple and economical to use and finally it should permit examination of the validity of hypotheses by providing calculated distributions which can be compared with experimental ones. Our purpose is to study the propagation of monoenergetic electrons in matter. A beam of electrons with normal incidence reaches the surface of a target considered as semi-infinite, homogeneous and isotropic, and made up of atoms sufficiently far apart to make neighbouring interactions independent. A convenient analytical expression for the electronic energy distribution in the target has been obtained. Numerical values are calculated by means of a calculator and the results are compared with those obtained by Monte Carlo techniques. This method is simple and gives more accurate results. For this reason, if can be employed very easily by users of microanalytical techniques.