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Re: Light -photon "saturation"



Hi:

I am starting by accepting the model that a substance's lack of
transparency is due to the absorbtion of photons.

What if the substance were exposed to such an intense light that a
majority of its atoms were in an excited state? Would the substance then
become transparent to any additional light at this frequency?

Has (or could) something like this be done experimentally?

Ed Schweber

It's already been done. In the early sixties a grad student at
Cal, Sam McCall I think his name was, predicted the effect from
a numerical model (I don't remember the system either). He took
it to the lab, cranked up the light intensity, and observed the
previously undetected and unanticipated effect.

Leigh

(I just did an Alta Vista search on [transparency & "Sam McCall"]
and got one hit. When I followed it up nothing useful appeared.
On further searching I came up with other interesting leads, but
I have to prepare a couple of lectures for today. See, for example
http://www.phys.uni.torun.pl/~jkob/physnews97/node36.html ) and
follow links for "induced transparency".)