Attosecond relative time delays in streaked photoemission from Mg (0001) surfaces

We analyze attosecond relative time delays in the photoemission from conduction band (CB) and core levels (CL) of metal surfaces within a quantum-mechanical model. The relative delay between CB and CL photoelectrons is found to be sensitive to the electron mean free path and the screening of the NIR streaking field inside the solid. Our numerical results reproduce a recent attosecond-streaking experiment with an Mg(0001) surface [S. Neppl \textit{et al}., Phys. Rev. Lett. \textbf{109}, 087401 (2012)], which reveals no relative streaking time delay between CB and CL electrons.