Electron momentum spectroscopy of the isoelectronic species hydrogen fluoride and neon

The authors report new electron momentum spectroscopy (EMS) measurements on hydrogen fluoride (HF) and neon (Ne) at 1500 eV. The present HF data for the 1 pi , 3 sigma and 2 sigma orbitals are compared in detail with the results of an earlier EMS study at 400 and 1200 eV and with the results of a recent calculation of the valence orbital momentum distributions given by (i) SCF calculations at the Hartree-Fock limit and (ii) CI calculations of the complete molecule-ion overlap amplitude. The current Ne 2p and 2s momentum distributions are compared with the results of both the plane wave and a new, fully distorted wave Born approximation (DWBA) calculation. The results of the DWBA calculation in Ne have direct relevance to HF, in particular to the inner valence (2 sigma ) cross section.