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As I understand it most of how objects look is because of how photons interact with electrons and photons emitted when excited electrons fall to lower energy levels producing photons.

So if one traps a completely ionized mass of say iron or nickel and drew off the associated electrons what would the remaining plasma look like? To my way of thinking, it would have to be colorless. There is another bit of my brain telling me it can't be so. enlighten me.

Muze
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King-Ink
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2 Answers2

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It is extremely hard to reach any kind of density of "plasma" of just nuclei - the thought experiment of "drawing off" the electrons would be surprisingly hard in practice, as the net charge gets larger and larger so the energy required to remove one more electron gets astronomical very quickly.

Thus you would have a very low density "plasma" and if there are zero electrons, the mean free path of photons traveling through the medium would be such that there is no reflected light and it would look "black" (very dark grey) in reflected light. Most of the photons would travel right through (it would be mostly transparent).

So yes - most likely no "color" can be observed.

Floris
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    Thank you so much for your time. Why would it be dark? Do nucleons absorb photons? – King-Ink Jan 10 '16 at 16:35
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    Low probability of interaction - no reflected photons. – Floris Jan 10 '16 at 19:21
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    @Floris If there is low probability of interaction, it would be transparent, not black. – Christopher King Jan 11 '16 at 03:55
  • If the nuclei have a shadow, then we have to answer what happens to the light. If the light is absorbed, the heat would probably be radiated back out over time, if the light is reflected the nuclei, while very small, would reflect some light and not be completely black. A soup of positively charged nuclei would be very diffuse though as Floris points out, or under enormous pressure. Being so diffuse and so small a percentage of the space it occupies, I think transparent is probably the closest answer to what it would look like. – userLTK Jan 11 '16 at 05:32
  • @PyRulez - I specifically talked about "reflected light" of which there is very little. Which is the case for a black object. In my definition, "black" = no reflected photons. One could argue that "black is not a color", etc... – Floris Jan 11 '16 at 05:41
  • @PyRulez I think you are right that it would be transparent if you write it up as an answer. – King-Ink Jan 11 '16 at 14:40
  • I edited my answer to clarify that everything I said in my answer leads up to (but did not explicitly mention) transparency. – Floris Jan 11 '16 at 15:17
  • @King-Ink yeah, this answer is good now. – Christopher King Jan 11 '16 at 19:45
  • Sounds good to me. – King-Ink Jan 11 '16 at 20:54
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You can get a picture of the iron atom's shadow. You can see the nuclei's and electron's shadow.

enter image description here

http://news.nationalgeographic.com/news/2012/07/120710-first-picture-atom-shadow-photograph-science-nature-smallest/

Muze
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    While not a direct answer, that article somewhat related and interesting. (voted you up to undo the vote down). – userLTK Jan 11 '16 at 05:27