In principle you can have absorption of multiple photons in the photoelectric effect. In practice the probability is very very small under ordinary circumstances. If you had a strong enough laser beam you could probably observe the effect.
LeeH
Multiple (two) photon absorption to drive fluorescence is now used in some special microscopes. It does require well-focused lasers, as well as molecules which are good at absorbing those two photons. Mike W.
(published on 03/17/2009)
