Researchers at the Carnegie Institution of Washington (Washington DC, USA) have managed to make a remarkable alloy of hydrogen and oxygen from water! They used X-rays to dissociate water at high pressure to form a solid mixture, that is, an alloy, of molecular oxygen (O₂) and molecular hydrogen (H₂).

The researchers placed some water under an extremely high pressure, about 170,000 atmospheres (17 Gigapascals), using a diamond anvil and then beamed high-energy X-rays at the water. Nearly all the water molecules split and reformed as a solid alloy of O₂ and H₂. The X-rays are key to cleaving the O—H bonds in water. Without it, the water remains as a high-pressure form of ice known as ice VII. Ice VII is one of at least 15 kinds of ice that exist under various high pressure and variable temperature conditions.

Russell Hemley of the Carnegie Institution of Washington said "we managed to hit on just the right level of X-ray energy input. Any higher, and the radiation tends to pass right through the sample. Any lower, and the radiation is largely absorbed by the diamonds in our pressure apparatus."

The researchers subjected the alloy to a range of pressures and temperatures, and also bombardment with X-ray and laser radiation. Provided the alloy is kept at about 10,000 times atmospheric pressure at sea level (1 Gigapascal), it withstands the treatment. Although clearly a crystalline solid, more experiments are needed to determine the alloy's precise crystal structure.

"The new radiation chemistry at high pressure was surprising," said Wendy Mao of the Los Alamos National Laboratory in the USA. "The new alloy containing the incompatible oxygen and hydrogen molecules will be a highly energetic material." An explosive alloy!

Earth's most severe mass extinction - an event 250 million years ago that wiped out 90 percent of all marine species and 70 percent of land vertebrates - was triggered by a collision with a comet or asteroid, according to a team led by The University of Washington, Seattle, USA. Evidence is based upon elegant findings involving carbon molecules called buckminsterfullerenes (C₆₀, Buckyballs) with the gases helium and argon trapped inside their cage structures.

The scientists do not know the site of the impact 250 million years ago, when all Earth's land formed a supercontinent called Pangea. However, the space body left a calling card - a much higher level of complex carbon molecules called buckminsterfullerenes, or Buckyballs, with the noble (or chemically nonreactive) gases helium and argon trapped inside their cage structures. Fullerenes, which contain 60 or more carbon atoms and have a structure resembling a soccer ball or a geodesic dome, are named for Buckminster Fuller, who invented the geodesic dome.

The researchers know these particular Buckyballs are extraterrestrial because the noble gases trapped inside have an unusual ratio of isotopes. For instance, terrestrial helium is mostly helium-4 and contains only a small amount of helium-3, while extraterrestrial helium - the kind found in these fullerenes - is mostly helium-3.

"These things form in carbon stars. That's what's exciting about finding fullerenes as a tracer," according to Luann Becker, one of scientific team involved. The extreme temperatures and gas pressures in carbon stars are perhaps the only way extraterrestrial noble gases could be forced inside a fullerene, she said. These gas-laden fullerenes were formed outside the Solar System, and their concentration at the Permian-Triassic boundary means they were delivered by a comet or asteroid.