Abstract
The bound-free transition form factor ( kappa mod exp(iq.r) mod nlm) is calculated directly in spherical coordinates for both hydrogenic and Slater-type orbitals. Using the exact Coulomb wave (r mod kappa ) associated with the field -Z/r, extremely concise analytical expressions are derived for the integral irrespective of either the triad nlm or of the quantisation axis. Results are given in terms of Appell hypergeometric polynomials F1 of two variables.
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