By comparison, a blink lasts a lifetime – atoms can rearrange themselves within one 350 quadrillionths of a second. As reported in the latest issue of the prestigious journal Nature, scientists at the Center for Nanointegration (CENIDE) at the University of Duisburg-Essen (UDE), together with their colleagues from the University of Paderborn, have been able to observe the movement of a one-dimensional material in real-time. Their research confirms that the acceleration of the atoms could leave even a Porsche standing.
Everything that surrounds us in our everyday life is three-dimensional, no matter how small: salt crystals, pollen, dust – even aluminium foil has a certain thickness. The first truly two-dimensional material graphene, was first discovered just 15 years ago, and ever since it has been used in applications such as transparent displays due to its outstanding electronic properties.
Now, scientists are recognising the potential of one-dimensional systems: systems comprising a string of atoms lined up like pearls on a necklace. These wires, the thinnest in the world, are unstable, a fascinating effect which is not at all well investigated – a fact that Dr. Tim Frigge, working within Prof. Michael Horn-von Hoegen’s research group, set out to address.
Frigge’s sample consisted of two single chains of indium atoms on a silicon substrate. At temperatures above approximately -140°C, the atoms form long chains, making the system metallic and enabling the conduction of electricity. Below this temperature, however, the atoms slip together in pairs and form hexagons, turning the system into an insulator.
This transition takes place at lightning-speed, within just 350 femtoseconds. In order to study it, the researchers had to induce the process artificially, doing so several million times at a rate of 5000 times per second. In order to achieve this, they stimulated the material with an ultrashort laser pulse, which, despite the icy temperatures of around -243°C, triggered the transition into the chain-shaped metallic state that otherwise only occurs at higher temperatures. The system subsequently reverted back to its non-metallic state one atom after the other, like a row of falling dominos.
In order to observe this transition, the physicists shot an electron beam across their sample, using its diffraction to determine the position of the atoms. Taking such a diffraction image every 50 femtoseconds results in a kind of ‘molecular movie’: a film that shows the path of the atoms over the sample surface – ‘just like in a flip-book,’ Frigge explains.
The researchers’ atomic level film represents the first step towards understanding – and, if possible, controlling – one-dimensional systems. It is worth noting, too, that as well as the path of the atoms, their speed can also be measured: over the short distance, the atoms hit speeds of around 100 km/h – and this in tiny fractions of a second, boasting acceleration trillions of times higher than that of a Porsche.
Original publication: Frigge et al., Optically excited strutural transition in atomic wires at the quantum limit, Nature, doi: 10.1038/nature21432
Prof. Dr. Michael Horn-von Hoegen, Physics Faculty, 0203 379-1438, email@example.com
Editor: Birte Vierjahn, 0203/ 379-8176, firstname.lastname@example.org
Ulrike Bohnsack | idw - Informationsdienst Wissenschaft
Quantum optics allows us to abandon expensive lasers in spectroscopy
22.11.2017 | Lomonosov Moscow State University
Nano-watch has steady hands
22.11.2017 | University of Vienna
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
22.11.2017 | Business and Finance
22.11.2017 | Physics and Astronomy
22.11.2017 | Physics and Astronomy