Resonant excitation series at the Kr3p and Xe4p thresholds

A systematic comparison is presented between the gas-phase:and solid-phase features of the resonant core excitation series in 3p excited krypton and 4 p excited xenon. For the gases total ion yield spectra were recorded. For t he solids, photoemission yield (total electron yield) spectra were compleme nted with photoconductivity excitation spectra, recording electron transpor t in the conduction band. The gas-phase spectra were compared with predicti ons of recent theoretical work [M. Ohno, Phys. Rev. A 51, 1042 (1995)] and approximated by means of the simple Rydberg formula with constant quantum d efect. The core excitation series observed in the solids are analogous to t he Mott-Wannier valence exciton series, as transitions from the respective core levels into the lowest conduction band are dipole allowed. Similar to the case of valence excitons, the series Limit of these core excitons was f ound to correspond to a rise in the photoconduction signal, marking the ons et of direct transitions into the conduction band. However, the core excito n energies are close to the gas-phase Rydberg state energies, in contrast w ith the valence excitons that have binding energies considerably smaller th an the respective valence Rydberg states in the gas. The energies of the co re excitons observed cannot be described by means of the effective reduced exciton mass and the dielectric constant: the simple Mort-Wannier effective -mass model is inadequate for these excitons. [S0163-1829(99)09529-6].