Surface and volume photoemission spectral yield from silver

We defined surface and volume components of photoemission and an experimental process to separate them. The reflectance, transmittance, and photoelectric yield were measured from silver thin films for $p$ and $s$ polarizations, for front and back illumination through the silica substrate, for angles of incidence ranging from 0° to 75°, and for photon energy ranging from 3.5 to 4.5 eV. We calculate values of the index of refraction, the escape depth of the photoelectrons, and the surface to volume photoyield ratio. The consistency of these values with redundant sets of experimental data is evidence for the validity of our model which assumed no surface roughness. We show that plasma resonance is important but only because it is associated with particular distribution and orientation of the electric field. We suggest that in silver the photoelectric threshold for volume effect might be larger than that for surface effect.