April 3, 2006 – Scientists at the US Department of Energy’s Brookhaven National Laboratory have developed a method to initiate and spatially localize chemical reactions on a submicron scale, an achievement that could enable nanoscale etchings for tiny electronic circuits.
In a proof-of-principle experiment, a team of researchers attached titanium dioxide nanoparticles to the end of a conventional atomic force microscope (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. Separation of oxidized and unaffected areas of the dye was as little as 0.1µm; the researchers hope to increase the spatial resolution of the technique to affect changes molecule by molecule, or at the 1nm scale.
In effect, the altered AFM probe actively initiates and controls chemical reactions on a surface, explained Brookhaven Lab materials scientist Stanislaus Wong, in a statement.
Initially, the research will help scientists better understand the kinetics of the molecular-level reactions that govern how sunlight is converted into electricity — and even let them use different types of catalyst particles to change those kinetics, ultimately leading to more efficient solar cells. Another application would be to use the AFM tip “almost like an ultrafine pencil, to draw out areas that you would like to react” — such as etching nanoscale circuits, Wong noted.