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From: bill@utastro.UUCP (William H. Jefferys)
Newsgroups: net.physics
Subject: Re: No pencil/no paper problem.
Message-ID: <116@utastro.UUCP>
Date: Mon, 13-Feb-84 10:13:28 EST
Article-I.D.: utastro.116
Posted: Mon Feb 13 10:13:28 1984
Date-Received: Wed, 15-Feb-84 06:27:32 EST
References: <165@hou2g.UUCP>
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 27

>> Everyone knows that Fermions obey Pauli statistics - i.e. no two
>> Fermions can be in the same state at the same time.  That is why
>> atomic orbitals become filled when 2 electrons (of opposite spin)
>> occupy them.
>> 
>> Now, when an atom is in a magnetic field the spectral lines get split
>> due to the Zeeman effect.  So what used to be identical electron states
>> (except for spin) are now correspond to entirely different energy levels.
>> Question - since the electrons in these new states now have no Pauli
>> partners, why don't electrons from higher energy orbitals cascade into
>> unpaired states of lower energy?

There is a confusion here between "energy levels" and "states".  The
correct rule is that no two fermions can be in the same state, as Jim 
says in the first line.  In an unperturbed atom there are two distinct 
states of lowest energy which are distinguished only by the spin of the 
electron.  The energies of these two states just happen to be the same.
When a magnetic field is introduced, the energies of these two states 
are different because the magnetic moment of the electron in the two 
spin states interacts with the external magnetic field differently.  
There are still only two states, except now their energies are different.
-- 

	Bill Jefferys  8-%
	Astronomy Dept, University of Texas, Austin TX 78712   (USnail)
	{ihnp4,kpno,ctvax}!ut-sally!utastro!bill   (uucp)
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