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Re: halogen bulbs



But Joe failed to mention that these bulbs have been BANNED from our campus
under pain of expulsion or loss of tenure! ;-(

Rick


-----Original Message-----
From: Joseph Bellina <jbellina@saintmarys.edu>


As I recall, hexaflourides of the metals form on the cold surface. The
hexaflouride is volatile, and unstable at the temperature of the
filament, so when the molecule hits the filament, it decomposes so that
the metal is deposited and the fluorine is free to do its thing.

Because of the high temperature of the filament, the deposited metal
atoms have some mobilitiy and can migrate enough to find a preferred
binding site so that in time a single crystal forms. Many of these are
nucleated on the surface of the wire, so the aggregate is a set of small
single crystals on the surface.

hope this helps your understanding.

cheers