Nonlocal Effects in Photoemission Studies with Nonnormally Incident Light

The local theory for the photoyield resulting from $p$-polarized light incident upon a half-space photoemitter is reviewed and generalized to include nonlocal effects. Local and nonlocal yields for the electron gas are presented for frequencies above the plasma frequency. The nonlocal yields are substantially higher than the corresponding local yields and it is shown that this enhancement involves nondirect electronic transitions associated with both plasmons and single-particle excitations.