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The discovery

During an intense working week in the autumn of 1985, Robert Curl, Harold Kroto and Richard Smalley made the completely unexpected discovery that the element carbon can also exist in the form of very stable spheres. They termed these new carbon balls fullerenes.

The carbon balls are formed when graphite is evaporated in an inert atmosphere. Usually they contain 60 or 70 carbon atoms. A new carbon chemistry has developed around these spheres. It is possible to enclose metals and noble gases in them, to form new superconducting materials with them and to create new organic compounds and polymeric matter for them.

The discovery of the fullerenes shows how unexpected and fascinating results can be created when scientists with different experience and research objectives collaborate.

 

An idea from outer space

Kroto's special interest in red giant stars rich in carbon led to the discovery of the fullerenes. For years, he had had the idea that long-chained molecules of carbon could form near such giant stars. To mimic this special environment in a laboratory, Curl suggested contact with Smalley who had built an apparatus which could evaporate and analyze almost any material with a laser beam. During the crucial week in Houston in 1985 the Nobel laureates, together with their younger co-workers J. R. Heath and J. C. O'Brien, starting from graphite, managed to produce clusters of carbon consisting mainly of 60 or 70 carbon atoms. These clusters proved to be stable and more interesting than long-chained molecules of carbon. Two questions immediately arose. How are these clusters built? Does a new form of carbon exist besides the two well-known forms graphite and diamond?

The read-out from the mass spectrometer shows how the peaks corresponding to C60 and C70 become more distinct when the experimental conditions are optimised.

 

 Schematic drawing of Smalley's cluster apparatus for the laser evaporation of graphite. The carbon clusters are formed in the helium gas flow and then analysed with mass spectrometry.

 

A famous building inspired the solution

 

 

For the 1967 World Exhibition in Montreal the architect R. Buckminster Fuller designed a spherical building which 18 years later gave the clue to the structure of the carbon clusters. He used hexagons and a small number of pentagons to create "curved" surfaces. This year's Nobel Prize laureates assumed that the cluster of 60 carbon atoms - C60 - consists of 12 pentagons and 20 hexagons with carbon atoms at each corner, the same form as a European football. They called the new carbon ball, C60, buckminsterfullerene. In colloquial English the carbon balls became "buckyballs".

 



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