Re: IR-absorption close to electronic absorption edge

Jan Beyer wrote:
Marvin schrieb am 28.09.2007 18:07 Uhr:
when looking at FTIR-spectra of e.g. Ge close to the electronic
absorption
edge, I see, that the transmittance is high in the low-energy-part, of
course, but it is not constant up to the band-gap-energy. It decreases
slowly. I tried to find some information about it, and somehow the
refractive index n seems to go up there. But I unfortunately didn't
<snip>
The refractive index of a substance always changes sharply near an
absorption edge or peak. See http://en.wikipedia.org/wiki/Refractive_index
or a good optics text.
Thanks for the answer!
But is there some "easier" (=more handwaving) argument than
Kramers-Kronig-relations? I'm trying to help undergraduate students...

Sorry for being so persistent...

Even more thanks in advance! ;-)

Jan

The Wikopedia entry is as basic as anything I've ever seen on this topic. Do you want to get into the expression of refractive index as a complex number, with a real part and an imaginary part? Personally, I never heard of this detail before graduate school.
.

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