Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCI gold chain study gets to heart of matter

29.08.2002


Discovery reveals smallest size molecules form functional structures; nanotechnology, research implications may be significant



While it may not make much of an anniversary present, a gold chain built atom by atom by UC Irvine physicist Wilson Ho offers an answer to one of the basic questions of nanotechnology—how small can you go?

In the first study of its kind, Ho and his colleagues have discovered the molecular phase when a cluster of atoms develops into a solid structure, a finding that can have a significant impact in the future development of metal structures built at the molecular scale. The study—which appears on the Science Express website, a service of Science magazine—also suggests a limit on the tiniest size that electrically conductive molecules can be constructed, and it presents a new method for researchers to build and examine these structures.


"This research answers fundamental questions on how solids form from an assembly of single atoms," said Ho, the Donald Bren Professor of Physics & Astronomy and Chemistry. "It allows us for the first time to see matter form in its smallest unit, and it can have important implications for the construction of metallic nanostructures that can be used in catalysis, electronic circuits and data storage."
Ho, working with fellow UCI researchers Niklas Nilius and T. Mitch Wallis, employed a scanning tunneling microscope to build a chain of gold atoms in order to measure how electron states change as more atoms are added to the chain. Starting with a single atom and adding one at a time, the researchers succeeded in measuring the electrical conductivity in these states as the atoms shared electrons, and these measurements varied dramatically as atoms were added to the chain. The scanning tunneling microscope enabled the researchers not only to manipulate individual atoms but also to capture images of the chain and measure its properties. As a result, the researchers were able to obtain a clear connection between the geometry of the fabricated nanostructure and its electronic properties.

As the researchers added the fifth and sixth atoms, the chain began to exhibit the collective properties of a bulk structure, which is when atoms in a molecule lose their individual characteristics and assume those of the overall structure. It is at this point when a metallic molecule becomes conductive and can be used as an electrical conduit.

Ultimately, the gold chain reached 20 atoms long, although in principle there is no limit to how long a chain can be built. In measurements taken as the chain grew from six atoms to 20, the states for the electrons showed only small variations and had practically converged to show properties typical of solids with a larger number of atoms. Ho said that the consistency of these latter measurements further support the concept that a functional gold structure can be built with as few as six atoms.

"What these experiments provide is a new way to study the electronic properties of materials at a nanoscale," Ho said. "We have been able to build a gold bulk structure with six atoms, but in a larger scale, we are starting to answer the question of how many atoms are needed to build a material that has potential utility.

"While it is not practical to mass produce these chains as one-dimensional conductors, catalysts or data storage devices, these studies provide a scientific basis for future nanotechnology," he added. "The results from this research contribute to our understanding of the behavior of matter as a function of its size."

In further research, Ho and his colleagues are studying the electronic properties both of gold atoms constructed in a two-dimensional array and of a chain of silver atoms. Ho used gold in this study because of its unique electronic properties that can be readily observed and controlled through the use of a scanning tunneling microscope. By extending the present study to include other types of atoms, it would be possible to understand a wide range of materials such as alloys, magnets and catalysts at the nanoscale.

Nilius is a UCI postdoctoral researcher, and Wallis is a graduate student on leave-of-absence from Cornell University. The National Science Foundation funded the research.

Tom Vasich | EurekAlert!
Further information:
http://today.uci.edu/r

More articles from Physics and Astronomy:

nachricht Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>