The underlying mechanism for these remarkable phenomena has been fascinating to scientists for decades; especially the origin of the recently discovered molecular cluster (O2)4 in the dense solid, red oxygen phase.
Researchers from the Carnegie Institution's Geophysical Laboratory (GL), with colleagues* found that under pressure the molecules interact through their outermost electron clouds or "orbitals." Using a newly developed synchrotron technique at HPCAT, the lab's synchrotron facility at Argonne National Laboratory, the researchers found that the interaction of these half-filled orbitals increases with increasing pressure, changing the location of the orbitals, and bringing the four oxygen molecules together to form the (O2)4 clusters at a pressure about 10,000 times the atmospheric pressure (10 gigapascals). The study is published the week of August 4, in the Proceedings of the National Academy of Sciences.
"The molecular interaction in oxygen revealed by this study is due to the unique fact that oxygen's outmost orbital is half-filled with two unpaired electrons," explained Yue Meng, lead author of the study at HPCAT. "As the molecules are squeezed into smaller volumes at high pressure, electrons in the orbital inevitably move about, trying to pair with electrons in the neighboring molecules."
To study the dense solid phases of oxygen, the researchers developed the high-pressure inelastic X-ray scattering technique at the Advanced Photon Source, a high-brilliance synchrotron X-ray facility at Argonne. The technique uses the synchrotron X-ray beam to probe the electronic bonding change as a diamond anvil cell subjects a sample to many hundreds of thousands of atmospheres. The researchers combined their experimental results with theoretical calculations by collaborators to further reveal that there is an increasing interactions between the neighboring (O2)4 clusters in the red-colored oxygen, providing a mechanism for forming new bonding between the oxygen clusters in still higher pressure phases.
"The behavior of oxygen at high pressure demonstrates one of the most profound effects of pressure on matter, which transforms the colorless air we breath into colorful dense solids," continued Meng. "The drastic change in the appearance of this familiar gas is due to the bonding changes in oxygen induced by high pressure."
"This is the first demonstration of how new tools can be used to probe the subtle interactions between atoms and molecules that lead to the formation of entirely new crystal structures," said Russell J. Hemley, the GL's director. "These new structures may give rise to entirely new electronic, magnetic, and other physical properties that could lead to new technologies."
The formation of molecular clusters through the anti-bonding orbital called ?* is well known in organic chemistry and the electron delocalization in cluster orbitals provides several potentials for technical applications. "It is exciting to find that oxygen forms molecular clusters under high pressure through similar mechanism and this opens a possibility for new forms of materials at high pressure with potential for technical applications," Meng concluded.
In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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