Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Using probes to control chemistry - molecule by molecule

Using probes originally designed to detect and image topographical features on surfaces, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have demonstrated the ability to initiate and spatially localize chemical reactions on the submicron scale.

They have been able to reliably manipulate chemistry on a very, very small scale in contrast to normal beaker-type reactions carried out in bulk. Such "site-selective" chemistry, taken down to the molecule-by-molecule level, could lead to new ways to etch small-scale electronic circuits, the development of extremely sensitive chemical sensors, as well as a better understanding and control of chemical reactions such as those used to convert sunlight into electricity in solar cells.

"Atomic force microscopy (AFM) uses probes that are analogous to the stylus on an old-style record player," says Brookhaven Lab materials scientist Stanislaus S. Wong. However, as opposed to "feeling" the nature of slight variations of pits within record grooves, AFM probes normally detect intermolecular interactions, related to changes in surface chemistry. "What we’ve demonstrated in our work is the ability to alter the AFM probe so it can be used not just passively, to sense chemistry, but actively, to initiate or control chemical reactions on a surface," Wong said.

In their proof-of-principle experiment, Wong’s group attached titanium dioxide nanoparticles to the end of a conventional AFM probe and used it to photocatalytically oxidize selected sites on a thin film of photoreactive dye -- a model for understanding photocatalysis in solar cells. Mandakini Kanungo, a postdoctoral researcher in Wong’s lab, will describe this work in a talk at the 231st national meeting of the American Chemical Society (ACS) in Atlanta, Georgia, on Thursday, March 30, 2006.

In the experiment, oxidized and unaffected areas of the dye were often separated by a mere 0.1 microns (millionths of a meter). The hope is to increase the spatial resolution of the technique to affect changes molecule by molecule, or at the one-nanometer (billionths of a meter) scale, Wong says.

Being able to control chemistry at this level has many potential applications. First, it gives the scientists deeper insight into the kinetics of reactions at the molecular level when, for example, a catalyst triggers the in situ oxidation of a chemical in the presence of light. This reaction is important toward understanding how to convert sunlight into useable forms of energy such as electricity. A "close-up" view of the chemistry will allow scientists to experiment with different types of catalyst particles, sizes and shapes of particles, and other characteristics to see precisely how these changes affect the kinetics and other dynamic properties associated with the photocatalytic process. This work could ultimately lead to the design of more efficient catalysts and more efficient solar cells.

In another application, Wong says, "You can use the AFM tip almost like an ultrafine pencil to draw out areas that you would like to react. This creates nanometer-scale ’lines’ that are different from the chemistry of surrounding areas on the substrate." In essence, he says, you can etch out such "lines of reactivity," using chemistry to "draw," for example, nanoscale circuits. Such small-scale circuits could further shrink the scale of electronic devices, as well as increase the efficiency and/or speed of data storage and retrieval.

One important benefit of this technique is that it is environmentally friendly, Wong says, using no electric current or potentially harmful reaction conditions. Furthermore, the technique has such high specificity that it offers the potential for single-molecule detection and analysis -- a benefit with possible applications in refined chemical sensor technology. Such sensors might be able to detect as little as a single molecule of a potentially hazardous material released, for example, in a terror attack.

Karen McNulty Walsh | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Signaling Pathways to the Nucleus
19.03.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht In monogamous species, a compatible partner is more important than an ornamented one
19.03.2018 | Max-Planck-Institut für Ornithologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

A new kind of quantum bits in two dimensions

19.03.2018 | Physics and Astronomy

Scientists have a new way to gauge the growth of nanowires

19.03.2018 | Materials Sciences

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Science & Research
Overview of more VideoLinks >>>