Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Observing live phase transition - watching the atoms race

31.03.2017

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.


Electron beam (blue) which probes the structural change of the indium atom chains (red balls) upon excitation through a femtosecond laserpuls (violet). (Source: Dr. Andreas Lücke, Universität Paderborn)

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

Further information:
Prof. Dr. Michael Horn-von Hoegen, Physics Faculty, 0203 379-1438, horn-von-hoegen@uni-due.de

Editor: Birte Vierjahn, 0203/ 379-8176, birte.vierjahn@uni-due.de

Ulrike Bohnsack | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-duisburg-essen.de/

More articles from Physics and Astronomy:

nachricht MEMS chips get metatlenses
21.02.2018 | American Institute of Physics

nachricht International team publishes roadmap to enhance radioresistance for space colonization
21.02.2018 | Biogerontology Research Foundation

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>