Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

U of T team makes ’movie stars’ of atoms

21.11.2003


Chemists at the University of Toronto have captured atom-scale images of the melting process-revealing the first images of the transition of a solid into a liquid at the timescale of femtoseconds, or millionths of a billionth of a second.

The result is an unprecedented "movie" detailing the melting process as solid aluminum becomes a liquid. This new study, led by Professor R. J. Dwayne Miller of the Departments of Chemistry and Physics, received the prestigious cover position of the Nov. 21 issue of Science.

"Imagine being able to see atoms as they move in real time," says Miller, who holds the Canada Research Chair in Femtoscience. "Chemistry and biology are fundamentally governed by changes in atomic structure. We now have a tool that will let us observe the most fundamental processes at the atomic level of inspection with sufficient time resolution to allow us to see chemical and biological events as they happen."



Since no camera shutter can open and close at the femtosecond time scale, the team built a special system using a laser and an electron gun inside a vacuum chamber. The energy of the laser’s blast superheated small sections of the aluminum to over 1,000 degrees Celsius, exceeding the metal’s melting point of 660 degrees Celsius.

Releasing a 600-femtosecond electron pulse at virtually the same moment of the laser blast, they captured an image of the aluminum atoms. This revealed the melting process at 0.5-picoseconds (one thousandth of a billionth of a second) after the laser struck the aluminum. However, capturing the complete melting sequence required that they repeat the process several times, each time firing the electron pulse a few hundred femtoseconds later. This revealed the melting process at 1.5-, 2.5- and 3.5-picoseconds after the laser pulse.

The "movie" the group saw when they put the frames together revealed that the solid literally shook itself apart at the atomic level. Liquids are fundamentally different than solids in that the atomic positions are random in liquids but ordered in solids. The team was able to watch, step by step, as the initially well-ordered arrangement of aluminum atoms in the solid changed into the disordered state of the liquid. The aluminum melted in an astonishingly short time-within 3.5 picoseconds.

This work represents the first atomic level view of the melting process, one of the simplest structural changes of matter. The team stresses the scientific implications of being able to watch atoms rearrange themselves on the femtosecond timescale. "Chemists think of reactions in terms of atoms moving around as bonds are broken and formed," says Jason Dwyer, a graduate student in Miller’s laboratory and a co-author of the paper. "It is one of the dreams of chemistry to be able to actually watch that as it happens, and we now have a technique that lets us do that."


The research is funded by the Canada Foundation for Innovation, the Ontario Innovation Trust, the Natural Sciences Engineering Research Council of Canada and the U of T Connaught Fund.

CONTACT:

R.J. Dwayne Miller
Department of Chemistry
(currently in Germany)
011-49-30-897-48221 2-6pm EST
011-49-30-6392-1429 7am-12pm
dmiller@Lphys.chem.utoronto.ca

Brad Siwick
Department of Physics
416-978-0366
siwick@Lphys.chem.utoronto.ca

Jason Dwyer
Department of Chemistry
416-978-0366
jdwyer@Lphys.chem.utoronto.ca

Robert Jordan
Department of Chemistry
416-978-0366
robert@Lphys.chem.utoronto.ca

Nicolle Wahl
U of T Public Affairs
416-978-6974
nicolle.wahl@utoronto.ca

Nicolle Wahl | University of Toronto
Further information:
http://www.utoronto.ca/

More articles from Life Sciences:

nachricht Oestrogen regulates pathological changes of bones via bone lining cells
28.07.2017 | Veterinärmedizinische Universität Wien

nachricht Programming cells with computer-like logic
27.07.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Abrupt motion sharpens x-ray pulses

Spectrally narrow x-ray pulses may be “sharpened” by purely mechanical means. This sounds surprisingly, but a team of theoretical and experimental physicists developed and realized such a method. It is based on fast motions, precisely synchronized with the pulses, of a target interacting with the x-ray light. Thereby, photons are redistributed within the x-ray pulse to the desired spectral region.

A team of theoretical physicists from the MPI for Nuclear Physics (MPIK) in Heidelberg has developed a novel method to intensify the spectrally broad x-ray...

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

New 3-D imaging reveals how human cell nucleus organizes DNA and chromatin of its genome

28.07.2017 | Health and Medicine

Heavy metals in water meet their match

28.07.2017 | Power and Electrical Engineering

Oestrogen regulates pathological changes of bones via bone lining cells

28.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>