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Re: Quantum question?



At 10:43 PM -0800 1/27/00, Leigh Palmer wrote:


Thanks for the good info on 'lack of' collisional broaderning, esp. WRT the
.21m Hydrogen line and it's million year lifetime in the excited state.

(but I'm NOT gonna tell my kids about spending a million years in an
excited state just so one can have a perfectly narrow transition when
one DOES meet another body come'n thru the rye!)


Sure the Solid State crystal has periodic high spacial density, but
doesn't the same Exclusion Principle apply to two interstellar
hydrogen molecules when they get 'close'?

(I'm ASSUMING MOLECULES of H2 for some reason)


>Is this mechanism also describable as 'Pauli Exclusion' broadening,
>something that solid state folks use to explain the creation of
>conduction 'bands' as isolated atoms come close to each other.

No. The bands in a solid are a consequence of high spatial density
of electrons. (Well, the bands aren't, but the degenerate nature of
the electron distribution in the bands and the resulting unbound
high energy conduction electrons are consequences of Pauli exclusion.)

>There is a simple 'Kroenig-Penny' model that can be programmed
>eassily to illustrate the bands arising as the atoms (with their
>initial discrete levels) get closer together.

That is correct. The periodic nature of the crystalline potential
is responsible for the bands (that is, for the gaps between the
bands) in what would otherwise be a simple parabolic population
distribution in kinetic energy (N(E) ~ E^1/2) of electrons.

Leigh

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