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 Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center

nachricht A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country

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: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>