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Dear List--

Is there a physicist out there who can offer an intuitive explanation of 
how 2-photon absorption occurs?  I expect we all know that it isn't that 
there isn't any half-excited state that allows one photon to boost an 
electron half-way to the excited state, and the next photon to finish 
the job.  My sense is that it has to do with time-energy uncertainty (a 
la Heisenberg) but my quantum mechanics is elementary-school level.

Thanks!

Martin Wessendorf

-- 
Martin Wessendorf, Ph.D.                   office: (612) 626-0145
Assoc Prof, Dept Neuroscience                 lab: (612) 624-2991
University of Minnesota             Preferred FAX: (612) 624-8118
6-145 Jackson Hall, 321 Church St. SE    Dept Fax: (612) 626-5009
Minneapolis, MN  55455                    e-mail: [log in to unmask]