QUANTUM ELECTRODYNAMICS OF THE INTERNAL SOURCE-X-RAY HOLOGRAPHIES - BREMSSTRAHLUNG, FLUORESCENCE, AND MULTIPLE-ENERGY X-RAY HOLOGRAPHY

Quantum electrodynamics (QED) is used to derive the differential cross sections measured in the three new experimental internal source ensem ble x-ray holographies: bremsstrahlung (BXH), fluorescence (XFH), and multiple-energy (MEXH) x-ray holography. The polarization dependence o f the BXH cross section is also obtained. For BXH, we study analytical ly and numerically the possible effects of the Virtual photons and ele ctrons which enter QED calculations in summing over the intermediate s tates. Far the low photon and electron energies used in the current ex periments, we show that the virtual intermediate states produce only v ery small effects. This is because the uncertainty principle limits th e distance that the virtual particles can propagate to be much shorter than the separation between the regions of high electron density in t he adjacent atoms. We also find that using the asymptotic form of the scattering wave function causes about a 5-10 % error for near forward scattering.