Atomic scattering factors for K-shell and L-shell ionization by fast electrons

Atomic scattering factors have been calculated for K-shell ionization for e lements in the range Z = 6 (carbon) to Z = 50 (tin) and for L-shell ionizat ion in the range Z = 20 (calcium) to Z = 60 (neodymium). The calculations a re based on relativistic Hartree-Fock wave functions for the atomic bound s tates and Hartree-Slater wave functions for the continuum wave functions. T he results are presented in tabular form such that accurate values of the s cattering factors can be obtained by cubic spline interpolation for inciden t electron energies between 50 and 400 keV and for scattering vectors with magnitude s = sin theta/lambda up to 2.5 Angstrom(-1) (2 theta is the scatt ering angle and lambda the wavelength of the incident electrons). A separat e parameterization of the form factors is given for 2.5 less than or equal to s less than or equal to 20 Angstrom(-1), where they are small. In additi on, a simpler but less accurate parameterization of the atomic scattering f actors in an exponential form has been obtained by fitting the calculated f orm factors in the region s less than or equal to 2.5 Angstrom(-1). The sca ttering factors are suitable for the calculation of ionization cross sectio ns for use in atom location by channelling-enhanced microanalysis (ALCHEMI) .