Could you explain the significance of your article to the non-specialist?

The way things fall apart evidently includes key information on what keeps them together. This is analyzed in detail by investigating the fragmentation behaviour of small transition metal doped gold clusters upon energetic excitation with laser light. Competing decay channels - the evaporation of monomers and dimers - were explored with mass spectrometry, and quantified with statistical evaluations of decay rate constants. Evidence for enhanced stability of specific sizes and compositions supports simple predictions of the electronic shell model and the formation of centrally doped caged gold clusters.

What has motivated you to conduct this work?

Material properties strongly depend on their chemical composition, as is well documented for metal alloys. For small particles, composed of less than 100 atoms, expectations therefore are that changing just a few or even only one atom may result in drastic changes of their properties. This may in particular be the case for transition metals where subtle changes in the electronic structure have far reaching consequences on their chemical behaviour. In this context we study the influence of single atom doping in small noble metal clusters.

Where do you see this work developing in the future?

Further fundamental studies to directly study the structure of small doped clusters experimentally are needed. Challenges are to image binary clusters with elemental contrast down to sizes of a nanometer (corresponding to less than 20 atoms), either directly, for instance with transmission electron microscopy, or indirectly, for instance with spectroscopy. With increasing evidence for the existence of golden cages incorporating dopant atoms that at the same time show enhanced stability, one may imagine their use as building blocks for new materials. This opens up routes for the synthesis of materials with tailor-made functions, for instance related to their optical and catalytic properties.

Are there any particular challenges facing future research in this area?

While the studies on doped gold clusters - including species with a caged structure - reported so far are predominantly limited to small amounts generated by cluster beam methods, any application will rely on the availability of larger quantities. This will imply major steps forward in other - more bulky - synthesis methods.