Photoelectron Recapture Investigation in Ar Using Two-Dimensional Photoelectron Spectroscopy

``Complete'' two-dimensional photoelectron spectra of Ar in the vicinity of the $2p$ ionization thresholds have been measured allowing several features in the spectra to be explained. The photoelectron recapture probability above the $2p_{1/2}$ threshold has been studied by measuring directly the kinetic energies of the reemitted photoelectrons as a function of the photon energy. We find a recapture maximum at about 120 meV above the threshold. Our experimental results are compared with semiclassical calculations as well as with the quantum-mechanical calculation of Tulkki \textit{et al.} [Phys. Rev. A 41, 181 (1990)] and are found to be in moderate agreement.