High-Resolution Electron-Momentum Spectroscopy of Argon: Validation of Technique and Approximations

(e,2e) cross sections for argon have been measured for binding energies in the valence regime of the ion at energies of 500, 1000, 1500, and 1800 eV. The kinematic arrangement is noncoplanar symmetric. Cross sections are relatively normalized for each energy. The assumptions of electron-momentum spectroscopy are verified in detail. The distorted-wave impulse approximation with Hartree-Fock orbitals describes the data within experimental error. It gives the correct inner valence s orbital manifold cross section relative to the outer valence p manifold at all energies. Orbital manifolds of ion states are identified, within which cross-section ratios are independent of energy and recoil momentum. Spectroscopic factors are defined by the ratio of the cross section for an ion state to the cross section for the orbital manifold. The spectroscopic sum rule is verified