The Glow Of Liquid Metallic Hydrogen

[Mr. Milton Banana]

Hey folks,

I haven't been around in a while-figured I'd stop by here again. The gas giants fascinate the hell out of me. Liquid metallic hydrogen is one of the most common substances in our solar system and yet, we can only create it briefly here on earth due to the extreme pressures needed to do so. I've read that it glows. What causes it to glow, and how brightly? If there was a probe that could survive such a descent to the transition point where the liquid metallic hydrogen would begin-would we see this glow shine through to the top of the regular liquid hydrogen layer? I understand that on such planets, there really is no surface.

Also-have we taken pictures of liquid metallic hydrogen? What color is the glow? What kind of machine is used to create it here on earth?

[grant hutchison]

Shiny and reflective (like other metals), rather than glowing, I think.
The onset of this reflectivity has been taken as indicating the transition to the metallic state.
It's produced by squeezing the hydrogen between two diamond anvils, and as far as I know competing teams are still arguing with each other about whether either of them has really produced metallic hydrogen.

Grant Hutchison

[Mr. Milton Banana]

Grant...yes, I've also read that metallic hydrogen looks like liquid mercury.

[publiusr]

Some interesting reading on page 123 and page 160 in the Jan. 7 2021 issue of the journal SCIENCE:
“Crossover from hydrogen to chemical bonding” by Bogdan Dereka

This talks about a hybrid covalent-hydrogen bonded state where hydrogen bonds reach 45.8 kilocalories per mol
—from LiveScience

I wonder what this could point towards, if true.

[Tom Mazanec]

If we can only make it briefly, then it is not metastable like, say, diamond?
Disappointing.

[grant hutchison]

If we can only make it briefly, then it is not metastable like, say, diamond?
Disappointing.

Yes, if only diamond weren't metastable, we'd be able to do something useful with it.

(Metastability would be a good outcome, but it's likely to occur only at very high pressures.)

Grant Hutchison

[eburacum45]

Diamond can exist for billions of years, when confined at high pressures in a diamond pipe.

I don't know how long diamond can persist at normal sea-level pressure, but I've never heard of a diamond exploding into graphite spontaneously. Does this happen?

[grant hutchison]

Diamond can exist for billions of years, when confined at high pressures in a diamond pipe.

I don't know how long diamond can persist at normal sea-level pressure, but I've never heard of a diamond exploding into graphite spontaneously. Does this happen?

It does not. The degradation involves a slow transformation to graphite--you get that at high temperatures in diamond cutting tools. But at room temperature it would take billions of years.

Grant Hutchison

[eburacum45]

So metastable hydrogen metal might exist and persist, if only we can make it?

[cjameshuff]

So metastable hydrogen metal might exist and persist, if only we can make it?

It might, or might not. It might also require temperatures near absolute zero, or pressures high enough to make it of no practical use. There aren't actually theoretical predictions of metastability, just speculation that it might be possible.

[grant hutchison]

The paper I previously linked to (full text here) estimates the probability of molecular hydrogen nucleating out in the bulk of metallic hydrogen, and from that predicts that metallic hydrogen will be metastable with a very long lifetime down to about 10-20GPa (well below its formation pressure), and will be evanescent at lower pressures.

Grant Hutchison

[cjameshuff]

The paper I previously linked to (full text here) estimates the probability of molecular hydrogen nucleating out in the bulk of metallic hydrogen, and from that predicts that metallic hydrogen will be metastable with a very long lifetime down to about 10-20GPa (well below its formation pressure), and will be evanescent at lower pressures.

Right, my statement really should have been predicated with "at conditions close to STP".

[publiusr]

Now, I have heard about "super-chemistry" where molecules can have properties as if discrete atoms. Even they can show as waves:
https://www.livescience.com/19268-qu...molecules.html

Some problems here as with metallic hydrogen?
https://forum.nasaspaceflight.com/in...?topic=36890.0