Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Can the atomic liquid Hydrogen exist?

  1. Sep 11, 2012 #1
    Imagine that we have got some vessel under standard temperature and pressure filled with atomic Hydrogen inside and the electrons of these atoms have got the same spin and therefore they cannot join into Hydrogen molecules, so the process of recombination does not occur. Then we begin cooling the vessel lower 20.28 K (boiling point for molecular Hydrogen) temperature. The question is-what will happen? Will the atomic Hydrogen liquefy or will it remain in gaseous condition? Or maybe it will be turned into molecular Hydrogen?
     
  2. jcsd
  3. Sep 11, 2012 #2
    How do those electrons have the same spin? Its more like "if there are 2 electrons in 1 orbital, they WILL have antiparallel spins". What you said is just not possible.
     
  4. Sep 12, 2012 #3
    chill_factor
    I do not know if it possible to achieve this from the technical point of view, but just imagine that it is done. I would like to know:
    Well, this can happen in case of heavier elements, but not Hydrogen.
     
  5. Sep 12, 2012 #4

    DrDu

    User Avatar
    Science Advisor

  6. Sep 12, 2012 #5
    No, the reasoning is "if 2 electrons have parallel spins, they CANNOT go to the same orbital".

    Example in case - ortohelium.

    Both electrons have the same spin.
    THEREFORE they CANNOT share an orbital, such as the lowest, 1s one. If one electron winds up in 1s orbital, the lowest available one for the other is 2s orbital.

    This is an excited state - about 20 eV above the ground state where the electrons have opposite spins and both fit in 1s.

    It is possible to change the spin of an electron so as to go to 1s ground state. This, however, is extremely hard.

    The lifetime of orthohelium is quoted in the region of 8000 seconds - which is 2 hours. Does someone know what the decay process actually is?

    Now suppose you could somehow produce atomic hydrogen gas with aligned spins.

    Unless two hydrogen atoms can somehow change one electron spin to fit the electrons into a common orbital, they cannot form a bond - they repel and scatter off each other. And when they are not interacting, they have no reason to change spin. Thus spin aligned hydrogen cannot be described by single lifetime like orthohelium, because the specific speed of the process of spin reorientation events would depend on the specific frequency of interactions - temperature and density. In any case, it could be expected that the spin reorientation would be slow.

    If spin aligned hydrogen could be produced in large quantities, could it be cooled, in face of the infrequent spin flip caused recombinations releasing heat, to the extent that the atoms would under van der Waals forces condense into liquid or solid?
     
  7. Sep 12, 2012 #6
  8. Sep 13, 2012 #7
    DrDu
    Thanks! Very interesting! :shy:
    And did they succeed in it?

    snorkack
    And how this Helium is excited? By means of lasers? Magnetic field? Other methods?
    Well…….can you tell me how to calculate the necessary time for recombination? I opened the topic here https://www.physicsforums.com/showthread.php?t=624890 but nobody answered.
    Well, the recombination will slowly occur, the heat will be emitted and dispersed, so probably hydrogen will be cooled :wink:
     
    Last edited by a moderator: May 6, 2017
  9. Sep 13, 2012 #8

    DrDu

    User Avatar
    Science Advisor

    No, if I remember well, the problem was that spin flip is to rapid. This whole subject became a turn with the generation of Bose Einstein Condensates in the nineties in magnetic traps. AFAIK, BECs of Hydrogen atoms have not been prepared, yet.
     
  10. Sep 13, 2012 #9
    But what about the NASA patent the link of which you posted here? I read it, they say that it is possible to store solid atomic Hydrogen (page 3, BACKGROUND OF THE INVENTION). Why it is so difficult to store liquid atomic Hydrogen and relatively easy-solid one? :uhh:
     
  11. Sep 13, 2012 #10

    DrDu

    User Avatar
    Science Advisor

    Because the atoms are bound to the surface which creates an energetic barrier for recombination.
     
  12. Sep 13, 2012 #11

    atyy

    User Avatar
    Science Advisor

  13. Sep 14, 2012 #12

    DrDu

    User Avatar
    Science Advisor

    Oh, that's interesting. Good you found it!
     
  14. Sep 14, 2012 #13
    Trivially easy. Just about anything that ionizes helium and allows it to recombine.

    There is no guarantee that an electron which comes across a helium ion has opposite spin to the lone electron of the ion. Once the electron has recombined, even to a higher orbital than 2s, all decays changing electron spin are extremely unlikely, so orthohelium states will decay to the lowest available orthohelium state... which is long lived.
     
  15. Sep 14, 2012 #14
    DrDu
    And why it is difficult/impossible to do the same with liquid atomic Hydrogen?

    snorkack
    Ok, thanks :smile: and what can you say about this?
     
  16. Sep 15, 2012 #15
    The density and thus collision rate in a liquid (any liquid) is much higher than in the gas.

    The life time of the metastable state will be strongly affected by that.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Can the atomic liquid Hydrogen exist?
  1. Hydrogen atom shells (Replies: 4)

Loading...