[Phys-L] Re: Promises promises

[John Denker <jsd@AV8N.COM>]

On 07/10/05 13:28, Ludwik Kowalski wrote:
> As a physics teacher I should not miss an opportunity to correct a
> common error. The sentence: “The light excites an electron and prompts
> it to split with its corresponding ‘hole,’ or positive charge.” is
> disturbing. Photons do not excite electrons, they excite atoms and
> molecules. And electrons do not “split with” holes. Yes, I know the
> author is not a scientist; but I can not resist correcting such things.

1) Photons do excite electrons.  In the case of free
electrons this is obvious.  In the case of bound electrons
it is matter of taste whether you call it an excitation
"of the electron" or an excitation "of the overall system".

The language of free electrons is commonly applied to
electrons in semiconductors, for good reason.

2) Electrons do "split with" holes.

3) An electron-hole pair is in many ways analogous to an
excited state in an atom or molecule.

========

These are entirely conventional ideas and terminology
among scientists.  Look up the discussion of Frenkel
excitons and Mott-Wannier excitons in any solid-state
physics text.
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