First - Basic photoelectric effect demonstration setup: A charged battery with a gap in the metallic junction between the poles placed relatively close from each other, but not close enough for measurable current to occur spontaneously. Emit photons of sufficient energy towards the gap surfaces - sparks start flying. Is this correct? Second - Is compton scattering classifiable as a similar kind of phenomenom taking place in a different kind of situation? I've understood that Compton scattering occurs in a situation where you emit a photon at convenient angle and sufficient energy and it hits an atom/molecule causing an electron emission from the atom/molecule, leaving the atom in an ionized state as an immediate effect - later obviously the electron could be replenished from some other source. If you do this experiment in a void with a large margin to any electron attracting sites, would the emitted electron just continue along its movement vector through the void? Bonus question - Electron density on the surface of a metal can be set into oscillating motion with photons. You emit photons, energies of which are below the work function of the metal, thus causing no photoelectron emission, but plasmonic 'ripples' on the metallic surface. Is this correct? I would assume that the occuring plasmonic waves are different at different photon energies, but does the angle of the colliding photons affect them in any distuingishable way? Does it cause maybe increased phononic effect at steeper angles, and a more pronounced plasmonic effect at more tangential angles? Thanks in advance! I will ask a crazy bonus question if my world doesn't get turned upside down by the grace of someone more versed in the topic.