Surface photoeffect for metals: Energy and angular electron distributions

The nonlocal theory of the author for the surface photoeffect produced in metals by $p$-polarized light is used to obtain energy and angular electron distributions for a range of low to moderate excitation energies. Considering only the effects from single-particle excitations, the energy distribution curves have, in general, a roughly triangular shape with the peak occurring for initial states near the Fermi energy. There is also a high-energy tail due to damping. Features in the angular distribution curves include confinement to decreasing angles with increasing light frequency and low-angle structure resulting from damping. Very striking structure appears in the energy-resolved angular distributions when the light frequency $\omega$ is such that $\hslash \omega >E_F+\Phi$ where $E_F$ is the Fermi energy and $\Phi$ the work function. A number of significant changes, including a sharp increase in the total yield, occur in the various distributions when Landau damping sets in, that is, when the plasmon enters the single-particle-excitation region. Arguments are presented that there is no reason to expect that the nonlocal surface contributions to the yield should vanish above the plasma frequency.