Simulation of attosecond streaking of electrons emitted from a tungsten surface

First time-resolved photoemission experiments employing attosecond streaking of electrons emitted by an extended ultraviolet pump pulse and probed by a few-cycle near-infrared pulse found a time delay of about 100 as between photoelectrons from the conduction band and those from the $4f$ core level of tungsten. We present a microscopic simulation of the emission time and energy spectra employing a classical transport theory. Emission spectra and streaking images are well reproduced. Different contributions to the delayed emission of core electrons are identified: larger emission depth, slowing down by inelastic-scattering processes, and possibly, energy-dependent deviations from the free-electron dispersion. We find delay times near the lower bound of the experimental data.