  The photoelectric effect established by Einstein is well known, which
indicates that electrons on lower energy levels can jump up to higher levels by
absorbing photons, or jump down from higher levels to lower levels and give out
photons1-3. However, how do photons act on electrons and further on atoms have
kept unknown up to now. Here we show the results that photons collide on
electrons with energy-transmission in semiconductors and pass their momenta to
electrons, which make the electrons jump up from lower energy levels to higher
levels. We found that (i) photons have rest mass of 7.287exp(-38) kg and
2.886exp(-35) kg, in vacuum and silicon respectively; (ii) excited by photons
with energy of 1.12eV, electrons in silicon may jump up from the top of valance
band to the bottom of conduction band with initial speed of 2.543exp(3) m/s and
taking time of 4.977exp(-17) s; (iii) acted by photons with energy of 4.6eV,
the atoms who lose electrons may be catapulted out of the semiconductors by the
extruded neighbor atoms, and taking time of 2.224exp(-15) s. These results make
reasonable explanation to rapid thermal annealing, laser ablation and laser
cutting.
