Dechanneling by Ionized Point Defects in Solids: Double Screening Effects

Abstract

The interaction between an external probe particle and host lattice is described by a screened Coulomb potential which gets modified due to the presence of impurities in the lattice. A double screened potential was earlier derived and we extend the formulation to include higher order terms in the dielectric function ε(q) which defines the screening parameters of this potential. The weakly decaying nature of the potential thus derived manifests itself in dechanneling process and scattering cross-section. It will also be evident from this formulation that the conduction electrons of the host lattice play an important role in the interaction between the probe particle and impurities. Dechanneling cross-sections are modified for various charge states of impurity in different planar directions when we consider the effect of both atomic electrons of the impurity and conduction electrons of the host lattice. The results for α-particle dechanneling in palladium (by C or H impurities) and for muon dechanneling by oxygen in tantalum are compared with earlier calculations and available experimental results.