http://www.fas.org/sgp/othergov/doe/lanl/pubs/00285799.pdf This phenomenon, multiple-photon excitation, is the absorption of many infrared
photons of the same frequency by a single
molecule. Observation of this phenomenon
was only possible with the high light intensities typical of lasers. It was a surprising
effect because multiple-photon excitation did
not fit the established theoretical pictures of
how molecules absorb radiation. While considerable experimental and theoretical work
has now been directed toward understanding
this phenomenon, much remains to be explained.
how do you think a microwave heats up atoms?
if atoms must emit a photon for every photon they absorb
then the electrons would not need several energy levels
(higher or lower orbits) for the electrons to move to or move from as they gain or lose energy.
you would never even get past room temperature.
