Related Experiment Video
Updated: Jun 3, 2026
10:01
In Situ High Pressure Hydrogen Tribological Testing of Common Polymer Materials Used in the Hydrogen Delivery Infrastructure
Published on: March 31, 2018
Bonding changes in hot fluid hydrogen at megabar pressures.
Natarajan Subramanian1, Alexander F Goncharov, Viktor V Struzhkin
1Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, DC 20015, USA. subbi@igcar.gov.in
Summary
Researchers used Raman spectroscopy to study dense hydrogen under extreme pressure and temperature. New techniques revealed modified intramolecular bonding and a potential phase transformation in this scientifically important fluid.
Area of Science:
- Condensed matter physics
- Planetary science
- Astrophysics
Background:
- Dense hydrogen is crucial for understanding planetary interiors and astrophysical phenomena.
- Previous studies were limited by the difficulty of probing hydrogen under extreme conditions.
Purpose of the Study:
- To investigate the bonding state and phase diagram of dense hydrogen.
- To explore the behavior of hydrogen at pressures up to 140 GPa and temperatures up to 1,500 K.
Main Methods:
- Utilized Raman spectroscopy with laser-heated diamond anvil cells.
- Developed novel techniques for containing and probing hot, dense fluid hydrogen.
Main Results:
- Observed discontinuous softening of the molecular vibron at high temperatures.
- Noted significant broadening and decreased intensity of roton bands.
- These changes indicate modified intramolecular bonding in dense hydrogen.
Conclusions:
- The findings suggest a pressure-induced transformation in fluid hydrogen.
- Results align with the presence of a temperature maximum in the melting line.
- This research advances our understanding of hydrogen's fundamental properties under extreme conditions.
Related Concept Videos
01:04Hydrogen Bonds
A hydrogen bond is formed when a weakly positive hydrogen atom already bonded to one electronegative atom (for example, the oxygen in the water molecule) is attracted to another electronegative atom from another polar molecule, such as water (H2O), hydrogen fluoride (HF), or ammonia (NH3). The huge electronegativity difference between the H atom (2.1) and the atom to which it is bonded (4.0 for an F atom, 3.5 for an O atom, or 3.0 for an N atom), combined with the very small size of an H atom...
00:26Hydrogen Bonds
Hydrogen BondsHydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.Hydrogen Bonds Control the World!Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are...
02:32Bonding in Metals
Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.
02:34Comparing Intermolecular Forces: Melting Point, Boiling Point, and Miscibility
Intermolecular forces are attractive forces that exist between molecules. They dictate several bulk properties, such as melting points, boiling points, and solubilities (miscibilities) of substances. Molar mass, molecular shape, and polarity affect the strength of different intermolecular forces, which influence the magnitude of physical properties across a family of molecules.
Temporary attractive forces like dispersion are present in all molecules, whether they are polar or nonpolar. They...
Temporary attractive forces like dispersion are present in all molecules, whether they are polar or nonpolar. They...
02:37Types of Chemical Bonds
Chemical bonding theories were pioneered by American chemist Gilbert N. Lewis. He developed a model called the Lewis model to explain the type and formation of different bonds. Chemical bonding is central to chemistry; it explains how atoms or ions bond together to form molecules. It explains why some bonds are strong and others are weak, or why one carbon bonds with two oxygens and not three; why water is H2O and not H4O.
02:49Bond Energies and Bond Lengths
Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, that is, the energy necessary to separate the bonded atoms. Separating any pair of bonded atoms requires energy — the stronger a bond, the greater the energy required to break it.