EVIDENCE FOR COULOMB INTERACTION BY BE VALENCE ELECTRONS BY COMPTON SCATTERING CROSS-SECTION MEASUREMENTS

The effect of Coulomb interaction on the Compton scattering cross‐section (CSCS) of a free electron gas has been calculated theoretically by Ohmura and Matsudaira within the framework of the random phase approximation (RPA). These calculations have shown that plasmon emission during the scattering process diminishes the CSCS against its value within the Hartree‐Fock approximation, which neglects the Coulomb interaction. A method is presented to measure relative values of the CSCS of metal valence electrons by separating the core electron part from the valence electron part of the Compton line profile. The relative values of the CSCS have been brought onto an absolute scale by means of a sum rule for the imaginary part of the dielectric constant given by Noziére and Pines. The measured values of the CSCS of Be valence electrons are in good agreement with the RPA calculations of Ohmura and Matsudaira. Copyright © 1969 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim