Resonant excitation series at the Kr 3p and Xe 4p 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 4p excited xenon. For the gases total ion yield spectra were recorded. For the solids, photoemission yield (total electron yield) spectra were complemented with photoconductivity excitation spectra, recording electron transport in the conduction band. The gas-phase spectra were compared with predictions of recent theoretical work [M. Ohno, Phys. Rev. A 51, 1042 (1995)] and approximated by means of the simple Rydberg formula with constant quantum defect. The core excitation series observed in the solids are analogous to the 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 found to correspond to a rise in the photoconduction signal, marking the onset of direct transitions into the conduction band. However, the core exciton energies are close to the gas-phase Rydberg state energies, in contrast with the valence excitons that have binding energies considerably smaller than the respective valence Rydberg states in the gas. The energies of the core excitons observed cannot be described by means of the effective reduced exciton mass and the dielectric constant: the simple Mott-Wannier effective-mass model is inadequate for these excitons.