by Staff Writers
Bochum, Germany (SPX) Jul 14, 2017
Chemists at Ruhr-Universitat Bochum have found evidence that carbon atoms cannot only behave like particles but also like waves. This quantum-mechanical property is well-known for light particles such as electrons or hydrogen atoms.
However, researchers have only rarely observed the wave-particle duality for heavy atoms, such as carbon. The team led by Prof Dr Wolfram Sander and Tim Schleif from the Chair for Organic Chemistry II together with Prof Dr Weston Thatcher Borden, University of North Texas, reports in the journal "Angewandte Chemie".
"Our result is one of few examples showing that carbon atoms can display quantum effects," says Sander. Specifically, the researchers observed that carbon atoms can tunnel. They thus overcome an energetic barrier, although they do not actually possess enough energy to do that.
Rarely observed for heavy particles
The researchers investigated the tunnel reaction using the Cope rearrangement, a chemical reaction that has been known for almost 80 years. The starting material for the reaction, a hydrocarbon compound, is identical to the product molecule. The same chemical compound thus exists before and after the reaction. However, the bonds between the carbon atoms change during the process.
In their experiment, the Bochum-based researchers marked one of the carbon atoms in the molecule: They replaced the hydrogen atom bonded to it with the hydrogen isotope deuterium, a heavier version of hydrogen. Molecules before and after the Cope rearrangement differed in terms of the distribution of the deuterium. Due to these different distributions, both molecular forms had slightly different energies.
Reaction shouldn't actually take place
This transition cannot, however, occur in the classic way - since, when rearranging from one form to the other, an energy barrier has to be overcome, although the molecule itself does not have the energy for this and the cold environment is also unable to provide it.
Although the new balance should not occur in the classic way, the researchers were nevertheless able to demonstrate it in the experiment. Their conclusion: the Cope rearrangement at extremely low temperatures can only be explained by a tunnel effect. They thus provided experimental evidence for a prediction made by Weston Borden over five years ago based on theoretical studies.
Solvents influence ability to tunnel
Beijing, China (SPX) Jul 10, 2017
Among various kinds of electrode materials for supercapacitors, carbon-based materials are most commonly used because of their commercially available and cheap, and they can be produced with large specific surface area. Heteroatom doping, especially dual-doped carbon materials have attracted much attention for the past few years, and have been regarded as one of the most efficient strategi ... read more
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet
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