space – Lightsources.org

Study reveals ‘radical’ wrinkle in forming complex carbon molecules in space

2019/09/032019/09/05

Unique experiments at Berkeley Lab’s Advanced Light Source shine a light on a new pathway for carbon chemistry to evolve in space.

A team of scientists has discovered a new possible pathway toward forming carbon structures in space using a specialized chemical exploration technique at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab). The team’s research has now identified several avenues by which ringed molecules known as polycyclic aromatic hydrocarbons, or PAHs, can form in space. The latest study is a part of an ongoing effort to retrace the chemical steps leading to the formation of complex carbon-containing molecules in deep space. PAHs – which also occur on Earth in emissions and soot from the combustion of fossil fuels – could provide clues to the formation of life’s chemistry in space as precursors to interstellar nanoparticles. They are estimated to account for about 20 percent of all carbon in our galaxy, and they have the chemical building blocks needed to form 2D and 3D carbon structures.

Image: This composite image shows an illustration of a carbon-rich red giant star (middle) warming an exoplanet (bottom left) and an overlay of a newly found chemical pathway that could enable complex carbons to form near these stars.
Credits: ESO/L. Calçada; Berkeley Lab, Florida International University, and University of Hawaii at Manoa.

Possible Path to the Formation of Life’s Building Blocks in Space

2018/03/052018/03/08

Experiments at Berkeley Lab’s Advanced Light Source reveal how a hydrocarbon called pyrene could form near stars

Scientists have used lab experiments to retrace the chemical steps leading to the creation of complex hydrocarbons in space, showing pathways to forming 2-D carbon-based nanostructures in a mix of heated gases.

The latest study, which featured experiments at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), could help explain the presence of pyrene, which is a chemical compound known as a polycyclic aromatic hydrocarbon, and similar compounds in some meteorites.

A team of scientists, including researchers from Berkeley Lab and UC Berkeley, participated in the study, published March 5 in the Nature Astronomy journal. The study was led by scientists at the University of Hawaii at Manoa and also involved theoretical chemists at Florida International University.

Image: A researcher handles a fragment and a test tube sample of the Murchison meteorite, which has been shown to contain a a variety of hydrocarbons and amino acids, in this photo from a previous, unrelated study at Argonne National Laboratory. Experiments at Berkeley Lab are helping to retrace the chemical steps by which complex hydrocarbons like pyrene could form in the Murchison meteorite and other meteorites.
Credit: Argonne National Laboratory

From Antarctica to the beamline, #weekendusers

2018/02/122018/02/21

A Belgian team is trying to find out about the origin of the Solar System by studying micrometeorites from Antarctica on the Dutch-Belgian beamline (DUBBLE).

Sør Rondane Mountains, Antarctica, 2013. Steven Goderis, from the Analytical Environmental and Geochemistry (AMGC) research group in the Vrije Universiteit Brussel (Belgium), is part of a Japanese-Belgian expedition looking for meteorites preserved in the cold and dry environment of the South Pole. And they hit the jackpot: they found 635 fragments of micrometeorites. After coming back with the precious load, similar meteorite recovery expeditions and field campaigns focusing on micrometeorites continued in the following years, all equally successful. To date, they have found hundreds of pieces of meteorites and thousands of pieces of micrometeorites.

So what is the point of micrometeorites? Of all the material reaching Earth from space only a small part will survive the heating and shock experienced upon entry in the atmosphere. The large majority of this material, the micrometeorites, will rain on Earth as extraterrestrial particles of less than 2mm in size. Although meteorites in general provide us with essential information on the origin and evolution of the planets and the Solar System, micrometeorites, mostly originating from the most primitive objects still remaining in the Solar System, raise an even higher scientific interest. “Any information we can get from micrometeorites will complement the knowledge we have of meteorites, so it is really important to study them. We have a wide array of samples so that we can get the best possible picture of these materials”, explains Bastien Soens, who is doing his PhD on this subject.

Image: The team on the beamline. From left to right: Niels de Winter, Bastien Soens, Dip Banerjee, Stephen Bauers and Niels Collyns.
Credits: C. Argoud.

Scientists observe nanowires as they grow

2018/02/082018/02/22

X-ray experiments reveal exact details of self-catalysed growth for the first time

At DESY’s X-ray source PETRA III, scientists have followed the growth of tiny wires of gallium arsenide live. Their observations reveal exact details of the growth process responsible for the evolving shape and crystal structure of the crystalline nanowires. The findings also provide new approaches to tailoring nanowires with desired properties for specific applications. The scientists, headed by Philipp Schroth of the University of Siegen and the Karlsruhe Institute of Technology (KIT), present their findings in the journal Nano Letters. The semiconductor gallium arsenide (GaAs) is widely used, for instance in infrared remote controls, the high-frequency components of mobile phones and for converting electrical signals into light for fibre optical transmission, as well as in solar panels for deployment in spacecraft.

To fabricate the wires, the scientists employed a procedure known as the self-catalysed Vapour-Liquid-Solid (VLS) method, in which tiny droplets of liquid gallium are first deposited on a silicon crystal at a temperature of around 600 degrees Celsius. Beams of gallium atoms and arsenic molecules are then directed at the wafer, where they are adsorpted and dissolve in the gallium droplets. After some time, the crystalline nanowires begin to form below the droplets, whereby the droplets are gradually pushed upwards. In this process, the gallium droplets act as catalysts for the longitudinal growth of the wires. “Although this process is already quite well established, it has not been possible until now to specifically control the crystal structure of the nanowires produced by it. To achieve this, we first need to understand the details of how the wires grow,” emphasises co-author Ludwig Feigl from KIT.

Image: A single nanowire, crowned by a gallium droplet, as seen with the scanning electron microscope (SEM) of the DESY NanoLab.
Credit: DESY, Thomas Keller

Cool engineering for cold science

2018/01/262018/01/26

Has there ever been life on Mars?

We’re not sure, and current investigations focus around what happened to the water on Mars, which has long since disappeared from the planet’s surface. In 2007, the Opportunity rover detected the presence of meridianiite at its landing site in Meridiani Planum. Meridianiite (also known as MS11) is MgSO₄∙11H₂O, a hydrated sulfate mineral that is only stable at temperatures below 2°C. Satellite observations tell us that there are outcrops of hydrated sulfate minerals, several kilometres thick, in the walls of Valles Marineris, and meridianiite is thought to be widespread on Mars. Could hydrated minerals such as these be locking away all the water that once flowed on Mars?

Ingredients for Life Revealed in Meteorites That Fell to Earth

2018/01/102018/01/17

Study, based in part at Berkeley Lab, also suggests dwarf planet in asteroid belt may be a source of rich organic matter

Two wayward space rocks, which separately crashed to Earth in 1998 after circulating in our solar system’s asteroid belt for billions of years, share something else in common: the ingredients for life. They are the first meteorites found to contain both liquid water and a mix of complex organic compounds such as hydrocarbons and amino acids.

Extraterrestrial Oceans

2018/01/092018/01/15

Exploring the solar system does not need spacecraft

One of the amazing things scientists can do at Diamond is to recreate conditions of other parts of the Universe. Recently they used this remarkable ability to peer into the salty waters hidden underneath kilometres of ice on Enceladus, one of Saturn’s moons.

In September, NASA ended the Cassini mission in spectacular fashion, crashing the spacecraft into Saturn. For twenty years, Cassini brought us closer to our gas giant neighbour and its moons. The probe made astonishing discoveries about one of them: Enceladus. This small moon has plumes of gas erupting from its surface, it has a rocky core covered in a thick layer of ice, and in between lies a deep, salty ocean. It is one of the most promising places to look for extraterrestrial life. Enceladus is one of the few places in the Solar System where liquid water is known to exist.

Spacecraft aren’t our only way of exploring the solar system, and Stephen leads a team of experimental astrophysicists based at Diamond and Keele University (UK), who have been recreating the conditions in Enceladus’s salty ocean right here in Harwell. They have been using Diamond’s astoundingly bright light to investigate one of the more mysterious properties of water – its ability to form clathrates when water is cooled under pressure. Clathrates are ice-like structures that behave like tiny cages, and can trap molecules such as carbon dioxide and methane.

Image Credit: LPG-CNRS-U. Nantes/Charles U., Prague.