Mechanically Polished Gold Surfaced Further Polished with Hydroxyl Radicals to Remove Nanoscopic Bumps in Joint Experiments by Researchers at Greifswald University in Germany and the University of Warsaw in Poland
Image Credit: Greifswald University and Wiley Interscience
The precious metal gold is used in many technical areas. It is a material of choice because it does not corrode - and because it also has interesting electrical, magnetic and optical properties. Gold is one of the most important metals in the electronics industry, in miniaturized optical components, and is used as an electrode material in electrochemical processes. It is extremely important that the surface of the gold is completely clean and smooth.
Conventional "polishing methods" result in an undesirable uneven path which limits access to the gold surface. Greifswald University Chair of Analytical and Environmental Chemistry, Institute of Biochemistry Fritz Scholz and a team from the universities of Greifswald and Warsaw have discovered a method that polish nanoscale bumps from a gold surface.
Conventional "polishing methods" result in an undesirable uneven path which limits access to the gold surface. Greifswald University Chair of Analytical and Environmental Chemistry, Institute of Biochemistry Fritz Scholz and a team from the universities of Greifswald and Warsaw have discovered a method that polish nanoscale bumps from a gold surface.
In the journal Angewandte Chemie, the scientists describe how hydroxyl radicals (OH radicals) can quickly remove any tiny bumps from mechanically polished gold surfaces, leaving a very smooth surface.
The researchers treated gold surfaces with Fenton's reagent, a mixture of hydrogen peroxide and iron (II) salts, which liberates OH-radicals. It is also used in the purification of waste water to remove organic contaminants.
It was unexpectedly found that the radicals would attack a polished, pure gold surface, says Scholz, because gold is known to be very difficult to oxidize. Experiments showed that the hydroxyl radicals oxidize gold very well. It is a measurable reaction. Surprisingly, however, oxidation continues only for as long as there are bumps on the gold surface
The researchers treated gold surfaces with Fenton's reagent, a mixture of hydrogen peroxide and iron (II) salts, which liberates OH-radicals. It is also used in the purification of waste water to remove organic contaminants.
It was unexpectedly found that the radicals would attack a polished, pure gold surface, says Scholz, because gold is known to be very difficult to oxidize. Experiments showed that the hydroxyl radicals oxidize gold very well. It is a measurable reaction. Surprisingly, however, oxidation continues only for as long as there are bumps on the gold surface
The researchers explain that the reaction of radicals with the gold atoms of the highly ordered completely smooth surface produces a stable layer of gold oxide, which may be without a significant loss of material again be reduced to elemental gold. In the bumps, the gold atoms are less organized and very reactive. During the oxidation, they detach themselves from the other gold atoms.
The very interesting new method to smooth gold surfaces has industrial chemical applications, says Scholz. OH-radical polishing procedure could be used to further stabilize gold medical implants. In some medical procedures, gold is used as a prosthesis, as well as tissue substitute in reconstructive surgery and electrode implants, such as implantable hearing aids. There is a tiny amounts of free gold that enters the surrounding tissue. The reason is probably an immune reaction caused by the OH radicals or similar species. Pre-treatment of gold implants with Fenton's reagent could prevent the release of gold particles into the body.
The very interesting new method to smooth gold surfaces has industrial chemical applications, says Scholz. OH-radical polishing procedure could be used to further stabilize gold medical implants. In some medical procedures, gold is used as a prosthesis, as well as tissue substitute in reconstructive surgery and electrode implants, such as implantable hearing aids. There is a tiny amounts of free gold that enters the surrounding tissue. The reason is probably an immune reaction caused by the OH radicals or similar species. Pre-treatment of gold implants with Fenton's reagent could prevent the release of gold particles into the body.
For more information:
http://www.techportal.de/de/0/2/news,public,newsdetail_public/1/start/,,,,/1204/
Fritz Scholz, Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17487 Greifswald (Germany), Fax: (+49) 3834-864-451 http://www.chemie.uni-greifswald.de/~analytik/
http://www.techportal.de/de/0/2/news,public,newsdetail_public/1/start/,,,,/1204/
Fritz Scholz, Institut für Biochemie, Universität Greifswald, Felix-Hausdorff-Strasse 4, 17487 Greifswald (Germany), Fax: (+49) 3834-864-451 http://www.chemie.uni-greifswald.de/~analytik/
Angewandte Chemie, Postfach 101161, 69495 Weinheim, Germany Angewandte Chemie, Postfach 101161, 69,495 Weinheim, Germany
