Coherent control of the angular distribution of electrons photoemitted from metal surfaces

We demonstrate that the angular distribution of electrons photoemitted from image states on a clean metal surface depends on the energies associated w ith the final electronic motion normal, E-z, and parallel, E-parallel to to the surface. The surface normal (z) over cap is the most probable directio n of ionization when E-z much greater than E-parallel to. But, for E-z appr oximate to E-parallel to, many electrons are ejected away from (z) over cap and the pattern of emission is altered dramatically. If a pump laser pulse produces a superposition of two image states, then the intensity and in ce rtain cases the direction of photoemission from this wave packet can be coh erently controlled via a probe pulse. [S0031-9007(99)09337-0].