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 Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>