Researchers at Delft University of Technology in The
Netherlands have developed a technique for generating atom clusters
made from silver and other metals. Surprisingly enough, these so-called
super atoms (clusters of 13 silver atoms, for example) behave in the
same way as individual atoms and have opened up a whole new branch of
chemistry.
If a silver thread is heated to around 900 degrees Celsius, it will generate vapour made up of
silver atoms. The floating atoms stick to each other in groups. Small
lumps of silver comprising for example 9, 13 and 55 atoms appear to be
energetically stable and are therefore present in the silver mist more
frequently that one might assume. Prof. Andreas Schmidt-Ott and Dr.
Christian Peineke of TU Delft managed to collect these super atoms and
make them suitable for more detailed chemical experiments.
The underlying mechanism governing this stability in super atoms was described in Science
by scientists from Virginia Commonwealth University in 2005. They had
discovered metal super atoms, but from aluminium. Their aluminium
clusters of 13, 23 and 37 atoms reacted in the same way as individual
atoms because they comprised electrons that revolved around the atom
cluster as a whole. These so-called outer layers were strikingly
similar to the outer layers of elements from the periodic table.
The super atoms gave the periodic table a third dimension as it
were, according to Schmidt-Ott: ‘The chemical properties of the super
atoms that have been identified up until now are very similar to those
of elements in the periodic table, because their outer layers are much
the same. However, we may yet discover super atoms with a different
outer layer, giving us another set of completely new properties.’
Schmidt-Ott hopes to find atom clusters with new unique magnetic, optical or electrical properties,
which would also be stable enough to create crystals or other solid
forms. Potential applications include catalysts in fuel and
extra-conductive crystals.
So although super atoms are nothing new, thanks to TU Delft the
particles can now be collected in a very pure form and selected
according to size, thereby making them suitable for chemical
experiments.
Full article can be read in the new edition of TU Delft magazine Delft Outlook. See http://www.delftoutlook.tudelft.nl
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