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Re: Absorbtion spectra



Absorption (or emission lines) are broadened by a variety of mechanisms.
Most of what is observed is Doppler broadening - atoms are in random thermal
motion which affects the actual frequencies absorbed and emitted. The
intrinsic width of the spectral line, essentially due to the time-energy
version of the Heisenberg Indeterminacy Principle, is too small to observe.
The energy levels can also be broadened by electric and magnetic fields,
especially when low dispersion spectroscopes are used.

************************************************************************
"Before I came here I was confused about this subject.
Having Listened to your lecture, I am still confused, but
on a higher level."
- Enrico Fermi
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George Spagna
Department of Physics
Randolph-Macon College
P.O. Box 5005
Ashland, VA 23005-5505
phone: (804) 752-7344 FAX (804) 752-4724
e-mail: gspagna@rmc.edu
http://www.rmc.edu/~gspagna/gspagna.html



-----Original Message-----
From: GARY HEMMINGER [mailto:Hemmig@D-E.PVT.K12.NJ.US]
Sent: Thursday, May 13, 1999 1:41 PM
To: PHYS-L@LISTS.NAU.EDU
Subject: Absorbtion spectra


A student has asked the following question which seems like a good
one to me:
If the black lines in an absorbtion spectra correspond to
individual wavelengths, then shouldn't they be too thin to be seen?
Any thoughts? Do they have a "width"?

*****************************************
Gary Hemminger
Dwight-Engelwood School
315 E. Palisade Ave.
Englewood, New Jersey
07631
e-mail: hemmig@d-e.org
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