In Vienna, researchers from Technical University have produced presumably cleanest water droplets of all time, according to ir own specifications. To produce this water without any impurities, in a vacuum chamber, ice from so-called ultra-Pure waters, which contains virtually no foreign matter, was produced at top of a metal pin. The vacuum chamber was cooled to minus 140 degrees Celsius. The so-created ice melted and produced cleanest water droplets in world, explained physicist Ulrike Diebold from TU Wien.
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The background for experiment is development of self-cleaning surfaces. Scientists from TU Wien and Cornell University in Ithaca, New York, jointly investigated surfaces treated with titanium dioxide. Titanium dioxide is often used for coatings, for example for mirrors that do not fogge even in humid environments. Really pure surfaces do not occur in nature, because in contact with ambient air always a thin layer of molecule is deposited. This layer can, however, noticeably change properties of materials.
Even tiny traces of air can be decisive
In microscopic investigations of surfaces coated with titanium dioxide, researchers had noticed that molecules were also deposited re in an orderly layer. At first, researchers did not know what substances it was. They suspected that this was a special configuration of water molecules. With help of absolutely pure water drop, it was possible to test how water behaves on titanium dioxide surfaces.
The result: water molecules did not order as regularly as previously found. The film from regularly arranged molecules was only created by air contact. So re were or substances involved in this film. Chemical analyses showed that it was acetic acid and ant acid. Although re were only tiny quantities of se substances in air, y were stored on surfaces under investigation.
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“The results show how careful we have to be in experiments of this kind,” Diebold said. Even tiniest traces of air, which actually appeared negligible, are sometimes decisive for course of scientific experiments.
