Tag: diamond anvil cell

Wet planets might evolve from dry, hydrogen-rich planets

Wet planets might evolve from dry, hydrogen-rich planets

Sub-Neptunes, or exoplanets 2–4 times Earth’s radius, are abundant in our galaxy. Models indicate that these exoplanets have rocky cores (the non-volatile interior) blanketed by envelopes of either hydrogen (dry gas dwarfs) or water (water worlds). 

In our own solar system, the water worlds of Uranus and Neptune orbit far from the sun, where temperatures are low enough for water to condense. This has led to the idea that water-rich planets form in the outer orbits of planetary systems, beyond what is known as the snow or ice line. They may then migrate inwards, to orbit closer to their star.

In recent years, however, large numbers of potentially water-rich exoplanets have been discovered in very close orbits. This is difficult to reconcile with the idea that such worlds can only form beyond the snow line.

The latest research by scientists from Arizona State University, The University of Chicago and the Open University of Israel suggests that water could be produced through chemical reactions at the boundary between a dry planet’s rocky core and hydrogen-rich atmosphere. This finding calls into question the idea that a planet’s composition is linked to where it formed. 

Researchers used the resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory. Their results were published in the journal Nature.

To explore the potential high pressure and temperature interactions between the hydrogen in the envelope and silicate in the core of dry planets at the core-envelope boundary, the team used the unique capabilities of the University of Chicago’s GeoSoilEnviroCARS beamline at 13-ID-D of the APS. This beamline’s high pressure, high temperature diamond anvil cell setup is designed to probe materials in-situ at extreme conditions to answer geochemical and geophysical questions across the pressure and temperature range of Earth and other planets. 

Read more on the APS website

Image: The high pressure, high temperature diamond anvil cell experiments suggest that reactions between dense hydrogen fluid and molten silicates on dry planets could generate substantial amounts of water. This hints at a potential way for dry, hydrogen-rich planets to evolve into watery worlds, challenging conventional planetary formation theory.

When carbon and nitrogen meet under pressure

When carbon and nitrogen meet under pressure

Three recent papers expand understanding of chemistry relevant to biology and industry

When it comes to the chemical elements, few are simultaneously as ubiquitous and necessary as carbon and nitrogen. They form the backbone of life, they enable many catalytic processes used in industry, they lie at the heart of many key materials in our everyday lives, and they make up over 78% of the composition of our atmosphere (almost all of that amount being nitrogen). Their chemistry has been widely studied for centuries, forming the foundation of organic chemistry and revealing entire libraries’ worth of reactions across inorganic chemistry. That chemistry forms the basis for common methods in mining, electroplating, pharmacology, and much more. But an international research team led by scientists at the Goethe University Frankfurt have shown that this familiar picture only accounts for a small fraction of what carbon and nitrogen can do—one just has to turn up the heat and the pressure. A series of studies published in the Journal of the American Chemical Society (JACS) and Angewandte Chemie International Edition reveal that under high pressure, carbon and nitrogen can simultaneously react with a variety of metals. The results could have a strong influence on future functional materials.

Carbon and nitrogen from very stable compounds. Molecular nitrogen N2 in the atmosphere, in particular, forms triple bonds that require a large amount of energy to break, and solid elemental carbon can be arranged to make diamonds, among the hardest and most corrosion-resistant compounds known. While carbon and nitrogen do react at ambient pressure forming cyanogen (CN)2  – a colorless toxic gas — their behavior can completely change under high pressure.  

However, the studies ley by scientists from the Goethe University Frankfurt revealed new pathways to make novel carbon-nitrogen anions through the use of extreme pressures. By pressing the reacting substances between two diamonds—in a device called a diamond anvil cell—while simultaneously heating the reactants at high precision using lasers, the team could get the nitrogen and carbon to bond together forming negatively charged ions, which are stabilized in novel compounds with positively-charged metallic ions.

Image: Using diamond anvil cells and laser heating, the research team has been able to produce new kinds of chemical reactions with ultra-stable carbon and nitrogen atoms, allowing them to form novel compounds with metals such as bismuth, cadmium, calcium, and europium.

Credit: Goethe University Frankfurt

Read more on DESY website

Asteroid impact in slow motion

Asteroid impact in slow motion

High-pressure study solves 60-year-old mystery

For the first time, researchers have recorded live and in atomic detail what happens to the material in an asteroid impact. The team of Falko Langenhorst from the University of Jena and Hanns-Peter Liermann from DESY simulated an asteroid impact with the mineral quartz in the lab and pursued it in slow motion in a diamond anvil cell, while monitoring it with DESY’s X-ray source PETRA III. The observation reveals an intermediate state in quartz that solves a decades-old mystery about the formation of characteristic lamellae in quartz hit by an asteroid. Quartz is ubiquitous on the Earth’s surface, and is, for example, the major constituent of sand. The analysis helps to better understand traces of past impacts, and may also have significance for entirely different materials. The researchers present their findings in the journal Nature Communications.

Large asteroid impacts can melt significant amounts of material from Earth’s crust (artist’s impression). Credit: NASA, Don Davis

Asteroid impacts are catastrophic events that create huge craters and sometimes melt parts of Earth’s bedrock.“ Nevertheless, craters are often difficult to detect on Earth, because erosion, weathering and plate tectonics cause them to disappear over millions of years,” Langenhorst explains. Therefore, minerals that undergo characteristic changes due to the force of the impact often serve as evidence of an impact. For example, quartz sand (which chemically is silicon dioxide, SiO2) is gradually transformed into glass by such an impact, with the quartz grains then being crisscrossed by microscopic lamellae. This structure can only be explored in detail under an electron microscope. It can be seen in material from the relatively recent and prominent Barringer crater in Arizona, USA, for example.

Read more on the DESY website

Image: Large asteroid impacts can melt significant amounts of material from Earth’s crust (artist’s impression)

Credit: NASA, Don Davis