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Thread: Metallic hydrogen apparently found

  1. #1
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    Metallic hydrogen apparently found

    https://gizmodo.com/after-an-80-year...inl-1841332239

    After an 80-Year Quest, Scientists Have Almost Certainly Discovered Metallic Hydrogen

    Ryan F. Mandelbaum
    Today 12:35PM
    Filed to: high-pressure physics

    Newly published results offer compelling evidence that hydrogen is a metal at extremely high pressures. But is the research enough to convince the field at large that metallic hydrogen exists? Theorists have long predicted that, at very high pressures (over 4 million times the pressure of the atmosphere at Earth’s surface), hydrogen should exist as a metal, a material that conducts electricity. Researchers have hunted for this material, at times ending up with dubious results. But in the past few years, teams in the U.S., France, and Germany have made strides at confining and compressing hydrogen and probing its properties at high pressure. A new paper finding the strongest evidence yet of metallic hydrogen has been peer reviewed and published—but search isn’t over yet.

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    https://www.nature.com/articles/s41586-019-1927-3

    Synchrotron infrared spectroscopic evidence of the probable transition to metal hydrogen
    Paul Loubeyre, Florent Occelli & Paul Dumas
    Nature volume 577

    Hydrogen has been an essential element in the development of atomic, molecular and condensed matter physics1. It is predicted that hydrogen should have a metal state2; however, understanding the properties of dense hydrogen has been more complex than originally thought, because under extreme conditions the electrons and protons are strongly coupled to each other and ultimately must both be treated as quantum particles. Therefore, how and when molecular solid hydrogen may transform into a metal is an open question. Although the quest for metal hydrogen has pushed major developments in modern experimental high-pressure physics, the various claims of its observation remain unconfirmed5,6,7. Here a discontinuous change of the direct bandgap of hydrogen, from 0.6 electronvolts to below 0.1 electronvolts, is observed near 425 gigapascals. This result is most probably associated with the formation of the metallic state because the nucleus zero-point energy is larger than this lowest bandgap value. Pressures above 40 gigapascals are achieved with the recently developed toroidal diamond anvil cell, and the structural changes and electronic properties of dense solid hydrogen at 80 kelvin are probed using synchrotron infrared absorption spectroscopy. The continuous downward shifts of the vibron wavenumber and the direct bandgap with increased pressure point to the stability of phase-III hydrogen up to 425 gigapascals. The present data suggest that metallization of hydrogen proceeds within the molecular solid, in good agreement with previous calculations that capture many-body electronic correlations.
    Last edited by Swift; 2020-Jan-31 at 06:22 PM. Reason: fix title
    Do good work. —Virgil Ivan "Gus" Grissom

  2. #2
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    We get one of these kind of reports every few years.

    2017 thread

    2016 thread

    I'd like to see some further work and some confirmation before I get too excited.
    At night the stars put on a show for free (Carole King)

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  3. #3
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    Chemical & Engineering News had some more information about the latest work.

    In the new study, Paul Loubeyre of the French Alternative Energies and Atomic Energy Commission and colleagues used an anvil with a new type of squeezing surface—a ring-shaped depression carved with an ion beam—and measured changes in their hydrogen sample’s infrared absorption. Above 400 GPa, Loubeyre’s group measured IR spectra indicating that the hydrogen sample had become metallic, which aligns with theoretical predictions.

    The research team and others agree that the results are most consistent with a metallic state of diatomic hydrogen molecules, rather than a metal of hydrogen atoms, which is the state with the most-sought-after properties. To show that the measurements weren’t the result of the diamond anvil’s deformation—an issue in some previous studies—the researchers reported data suggesting that the changes also reverse as the pressure decreases.

    The research has received measured praise from experts in the field, many of whom could be described as the Loubeyre group’s competitors or collaborators—or both—in the race to make metallic hydrogen. Several point out that while these optical measurements are consistent with a transition to a metallic state, there still could be other explanations, including another state of hydrogen, some change to the diamond’s structure, or an interaction between the hydrogen and the anvil. Similar optical results have also been reported by other groups. Loubeyre’s group appears to have reached a higher pressure than in those studies, although differences in how pressure is measured in these experiments make a clear determination difficult.
    At night the stars put on a show for free (Carole King)

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  4. #4
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    Wasn't one of the tasks that Juno had was to determine if there was metallic Hydrogen at Jupiter's core?

  5. #5
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    These days some question as to whether Jupiter even has a solid core anymore.

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