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 Beyond the brim, Sombrero Galaxy's halo suggests turbulent past
21.02.2020 | NASA/Goddard Space Flight Center

nachricht 10,000 times faster calculations of many-body quantum dynamics possible
21.02.2020 | Christian-Albrechts-Universität zu Kiel

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: A step towards controlling spin-dependent petahertz electronics by material defects

The operational speed of semiconductors in various electronic and optoelectronic devices is limited to several gigahertz (a billion oscillations per second). This constrains the upper limit of the operational speed of computing. Now researchers from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany, and the Indian Institute of Technology in Bombay have explained how these processes can be sped up through the use of light waves and defected solid materials.

Light waves perform several hundred trillion oscillations per second. Hence, it is natural to envision employing light oscillations to drive the electronic...

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

Im Focus: Skyrmions like it hot: Spin structures are controllable even at high temperatures

Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices

The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...

Im Focus: Making the internet more energy efficient through systemic optimization

Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.

Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.

Im Focus: New synthesis methods enhance 3D chemical space for drug discovery

After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.

"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Active droplets

21.02.2020 | Medical Engineering

Finding new clues to brain cancer treatment

21.02.2020 | Health and Medicine

Beyond the brim, Sombrero Galaxy's halo suggests turbulent past

21.02.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>