Attosecond spectroscopy of solids: streaking phase shift due to lattice scattering

Theory of laser-assisted photoemission from solids is developed for a numerically exactly solvable model with full inclusion of band structure effects. The strong lattice scattering in the vicinity of band gaps leads to a distortion and a temporal shift of the streaking spectrogram of the order of 100 as. The effect is explained in terms of Bloch electron dynamics and is shown to remain large for an arbitrarily small photoelectron mean free path. The implications for the streaking experiment on W(110) [A. L. Cavalieri et al., Nature (London) {\bf 449}, 1029 (2007)]