Our final piece in our Astronomy & You series is a fascinating piece on lab astrophysics and the discovery of buckminsterfullerene (c60) by Armagh Observatory and Planetarium’s own Michael Burton. He is our Director and before coming to Armagh was the Director of Teaching at the School of Physics in the University of New South Wales in Australia. He is also a member of the International Astronomical Union and President of the IAU’s Division B (“Facilities, Technology, Data Science”).
The discovery of some of the most bizarre compounds known – clusters of carbon atoms bound together in the form of a geodesic dome known as fullerenes – came from chemists trying to re-create the conditions of interstellar space in their laboratories.
The discovery of the fullerenes has influenced our conception of such widely separated scientific problems as the galactic carbon cycle, governing the cycling of materials between the stars and gas of interstellar space, and of classical aromaticity, a keystone of theoretical chemistry.
Many widely diverse research areas came together in the discovery of the fullerenes. This was inspired by trying to interpret astronomical observations made of gas clouds in space. The measurements were made using radio telescopes, applying the tool of microwave spectroscopy to analyse gas in space, from both stellar atmospheres and interstellar gas clouds.
In studying giant stars that are particularly rich in the element carbon, astronomers discovered spectral lines in their atmospheres that could be ascribed to a kind of long-chained molecule containing only hydrogen, carbon and nitrogen, termed cyanopolyynes. The same sort of molecules are also found in interstellar gas clouds. The inference was made that these carbon compounds had been formed in the atmospheres of stars and then expelled into space, rather than forming in interstellar clouds. This inspired chemists to examine how the formation of such long-chain molecules could occur by trying to re-create them in their laboratories.
When atoms in a gas condense to form clusters of atoms, a series of compounds are formed where the size of the clusters varies from a few atoms to many hundreds. In vaporising carbon and then observing the compounds that are subsequently formed – known as fullerenes – one particular cluster containing 60 carbon atoms (C60), was discovered. This has been dubbed buckminsterfullerene, after a geodesic dome designed by the architect Buckminster Fuller which contained 20 hexagonal (6-angled) and 12 pentagonal (5-angled) surfaces.
A whole new chemistry has since developed to manipulate these fullerene structures. New materials produced include superconducting salts of C60, new three-dimensional polymers, new catalysts, materials with novel electrical and optical properties for sensors. It has also been possible to produce thin tubes with closed end – nanotubes – arranged in the same way as fullerenes, forming materials of exceptional strength.