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Re: Collisional excitations

There seems to be a <major misconception> at work that keeps
cropping up in our postings. The correct statement is:
The coulomb force is not carried by photons!
The coulomb force is......
The......

Each charged particle carries its coulomb field around with it
everywhere it goes. When a charged particle approaches a neutral atom,
the coulomb field from the particle perturbs the orbits of the atomic
electrons (polarization). As the charged particle leaves the vicinity
of the atom, some of the perturbed orbits may "relax" into excited orbits
of the unperturbed atom. That is because a perturbed orbit is a mixture
of unperturbed orbits. The mixing of unpertured orbits thereby assigns
a probability to each state in the mixture of being the final "relaxed"
state of the atom.

Although I specified the target atom as "neutral", neutrality
is not at all necessary to the foregoing description.

The mixing of states is usually encountered in an elementary
quantum mechanics course during the study of the Stark effect.
Regards,
Jack

Adam was by constitution and proclivity a scientist; I was the same, and
we loved to call ourselves by that great name...Our first memorable
scientific discovery was the law that water and like fluids run downhill,
not up.
Mark Twain, <Extract from Eve's Autobiography>

On Tue, 19 Sep 2000, Philip Zell wrote:


I wonder how, during the inelastic collision between and electron and
an atom, resulting in electronic excitation of the atom, energy is
transferred from the free electron to the atom. It's an
electromagnetic interaction. The free electron and the orbital
electrons in the atom repulse each other (I believe one of you
mentioned that yesterday); will the electron, while it is
decelerating, emit a photon? Is it this photon that excites the
atomic transition?