The use of reduced parameters in many-beam electron diffraction theory

Abstract

Many-beam diffraction theory appears very complicated because of the number of parameters involved—e.g. beam voltage, g vector, orientation, atomic number, Debye-Waller factor. This complexity may be much reduced by multiplying the relevant equations by the primary extinction distance. Apart from simple lengths, the resulting parameters include orientation, dynamical interaction and the various ratios ξ_g/ξ_ng, ξ_g/ξ_ng’ which describe the forms of the real and imaginary potentials.

The diffracted intensities are discussed in terms of these parameters, which are shown to constitute an improved basis for the investigation of systematic many-beam effects. Particular attention is paid to the ratios ξ_g/ξ_ng and ξ_g/ξ_ng,’ since this approach would not be very useful if the diffraction were sensitive to these individually.