Wave-particle duality and the photoelectric effect

The wave-particle duality in light is a particularly mystifying problem in physics. One determining factor to demonstrate light to have particle characteristics is the photoelectric effect. The photoelectric effect is manifest as photons of a light beam with a given frequency are absorbed by a given material. When the energy of one photon is absorbed by the material, provided the net energy is greater than the electron binding force, the incoming photon will cause an electron in the outer level of an atom in the absorbing material to be ejected.

However, a recent experiment (as reported by Wired Science) conducted with FLASH, an x-ray laser in Hamburg, shot at xenon atoms yielded some interesting results. Apparently, the high frequency laser caused the inner level electrons to move violently and their displacement cascaded into a total of 21 electrons being ejected simultaneously. The common notion of a photon like a cue ball in billiards is now being reconsidered as the experiment suggests the photons working as a wave and not individual particles. Of peculiar interest is the fact that the photons penetrated to inner electron levels and not working from outside-in.