  In the attosecond (as) streaking of Cu 3s core-level photoemission of copper
dihalides, we predict theoretically that the satellite ($3d^9$) is emitted
later than the main line ($3d^{10}L^{-1}$; $L$: ligand). The emission time
delay is originated from the electron correlation between the core level and 3d
shell, which leads to the difference in core-hole screening between satellite
and main lines. Further, we find that the time delay corresponds to a
quantification of the extrinsic loss of photoemission.
