Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Watching the hidden life of materials

28.10.2014

Ultrafast electron diffraction experiments open a new window on the microscopic world

Researchers at McGill University have succeeded in simultaneously observing the reorganizations of atomic positions and electron distribution during the transformation of the “smart material” vanadium dioxide (VO2) from a semiconductor into a metal – in a time frame a trillion times faster than the blink of an eye. 


Prof. Siwick tweaking up the laser in his McGill University lab. CREDIT: Allen McInnis for McGill University

The results, reported Oct. 24 in Science, mark the first time that experiments have been able to distinguish changes in a material’s atomic-lattice structure from the relocation of the electrons in such a blazingly fast process.

The measurements were achieved thanks to the McGill team’s development of instrumentation that could be used by scientists in a variety of disciplines: to examine the fleeting but crucial transformations during chemical reactions, for example, or to enable biologists to obtain an atomic-level understanding of protein function. This ultrafast instrumentation combines tools and techniques of electron microscopy with those of laser spectroscopy in novel ways. 

“We’ve developed instruments and approaches that allow us to actually look into the microscopic structure of matter, on femtosecond time scales (one millionth of a billionth of a second) that are fundamental to processes in chemistry, materials science, condensed-matter physics, and biology,” says Bradley Siwick, the Canada Research Chair in Ultrafast Science at McGill.

“We’re able to both watch where nuclei go, and separate that from what’s happening with the electrons,” says Siwick, an associate professor in the departments of Chemistry and Physics. “And, on top of that, we are able to say what impact those structural changes have on the property of the material. That’s what’s really important technologically.”

By taking advantage of these recent advances, the research group has shed new light on a long-standing problem in condensed matter physics. The semiconductor-metal transition in Vanadium dioxide has intrigued the scientific community since the late 1950s.The material acts as a semiconductor at low temperatures but transforms to a highly conductive metal when temperature rises to around 60 degrees Celsius – not that much warmer than room temperature. This unusual quality gives the material the potential to be used in a range of applications, from high-speed optical switches to heat-sensitive smart coatings on windows.

The experiments took place in Siwick’s lab in the basement of McGill’s Chemistry building, where he and his team of grad students spent nearly four years painstakingly assembling a maze of lasers, amplifiers and lenses alongside an in-house designed and built electron microscope on a vibration-free steel table.

To conduct the experiments, the McGill team collaborated with the research group of Mohamed Chaker at INRS EMT, a university research centre outside Montreal. The INRS scientists provided the high quality, extremely thin samples of VO2 – about 70 nanometers, or 1000 times smaller than the width of a human hair– required to make ultrafast electron diffraction measurements.

The diffraction patterns provide atomic-length-scale snapshots of the material structure at specific moments during rearrangement. A series of such snapshots, run together, effectively creates a kind of movie, much like an old-fashioned flip book. 

 “This opens a whole new window on the microscopic world that we hope will answer many outstanding questions in materials and molecular physics, but also uncover at least as many surprises.  When you look with new eyes you have a chance to see things in new ways,” Siwick says.

The research was supported by the Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chairs program, and the Fonds du Recherche du Quèbec-Nature et Technologies.

``A photoinduced metal-like phase of monoclinic VO2 revealed by ultrafast electron diffraction``, Vance R. Morrison, Robert P. Chatelain et al, Science, Oct. 24, 2014.
DOI: 10.1126/science.1253779
http://www.sciencemag.org/content/346/6208/445.full 

Contact Information

Contact: Prof. Bradley Siwick
Organization: Departments of Physics and Chemistry

Secondary Contact Information

Contact: Chris Chipello
Organization: Media Relations Office
Office Phone: 514-398-4201

Chris Chipello | Eurek Alert!
Further information:
http://www.mcgill.ca/newsroom/channels/news/watching-hidden-life-materials-239767

Further reports about: Electrons INRS McGill VO2 dioxide experiments materials microscopic physics semiconductor snapshots structure

More articles from Materials Sciences:

nachricht Brilliant glow of paint-on semiconductors comes from ornate quantum physics
17.01.2019 | Georgia Institute of Technology

nachricht Viennese scientists develop promising new type of polymers
15.01.2019 | Vienna University of Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

Im Focus: Mission completed – EU partners successfully test new technologies for space robots in Morocco

Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.

Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Brilliant glow of paint-on semiconductors comes from ornate quantum physics

17.01.2019 | Materials Sciences

Drones shown to make traffic crash site assessments safer, faster and more accurate

17.01.2019 | Information Technology

Ultra ultrasound to transform new tech

17.01.2019 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>