Buckyball discovery kindled scientific furor

Many chemical elements occur in different physical forms called allotropes. For years carbon was thought to have two allotropes, graphite and diamond. Then, in the mid-1980s, a third appeared on the scene in the shape of a tiny sphere containing 60 carbon atoms. The new allotrope was named buckminsterfullerene in honor of R. Buckminster Fuller because its carbon-bonding pattern closely mirrors the skeletal structure of his architectural invention – the geodesic dome.

This tongue-twisting name was soon abbreviated to ‘buckyballs.’ A number of potential uses for buckyballs have been proposed or found but one of the most intriguing aspects of their discovery was the scientific furor they aroused. It dispels the notion that science is always conducted in an atmosphere free of the emotions and rivalries that govern most human affairs.

The first paper to announce the existence of buckminsterfullerene appeared in the Nov. 14, 1985, issue of Nature. The article carries the names of the three principal investigators and describes how the discovery was made by vaporizing carbon off a rotating graphite disk by means of a laser beam. The article is accompanied by a picture of a soccer ball and the statement that, if every vertex on the seams were replaced by a carbon atom, it would be a model for the new molecule. This is at the crux of the controversy that Gary Taubes tried to sort out in the Sept. 27, 1991, issue of Science.

At the heart of the matter was Harold Kroto, a British chemist interested in molecules existing between the stars, along with Bob Curl and Richard Smalley of Rice University. In 1984, Kroto told Curl of strange spectral lines coming from deep space that he thought may be coming from long chains of carbon atoms but that he had no way of proving it. Curl and Smalley were using a laser device to produce large molecules in the vapor state. Perhaps, he told Kroto, his mysterious interstellar molecule could be made in their machine.

Smalley was approached with the idea and, although hesitant to set aside his research for what seemed a quixotic quest, finally agreed to give it a try. On Sept. 1, 1985, they placed a graphite disk in the laser and the experiment got underway. Three days later a molecule with a molecular weight equal to 60 carbon atoms, and with a spectrum very similar to that Kroto found in his deep space spectrums, appeared in the vapor.

Smalley and Kroto differ on what happened next. Smalley’s version is that he came up with the spherical structure of alternating hexagons and pentagons and showed it to a colleague who said, “What you have there is a soccer ball!” Smalley says he then made a paper model of the molecule but had to work to convince Kroto, a contention the latter called, “patently false.” Kroto maintains his introduction of the geodesic dome concept led to the final structure for the molecule.

Both published extensively arguing that their version of the events was the correct one. In 1996, Smalley, Curl, and Kroto were jointly awarded the Nobel Prize in chemistry “for discovery of a new class of carbon molecule.” A complete account of the controversy may be found in Hugh Aldersy-Williams’ 1995 book, “The Most Beautiful Molecule: The Discovery of the Buckyball.”

As with any new discovery, the hunt was quickly on to find a use for this unique carbon molecule but the search was hampered initially by the fact that very little of the material existed. Initially, samples of pure buckyballs cost well in excess of $1,200 per gram. Then, in the Sept. 27, 1990, issue of Nature, University of Arizona professor Donald Huffman gave a simplified means of preparing workable quantities of buckyballs by the evaporation of graphite electrodes. This spurred the search and, over the next decade, papers have appeared citing dozens of potential uses for the molecule ranging from chemical catalysts and the separation of gas molecules to enhancing bone images while doing a magnetic resonance imaging scan.

A report in the July, 1993, issue of the National Science Foundation’s Research News said that it is possible to cage atoms of radioactive radon in the hollow buckyballs and then inject these into cancerous tumors so that emitted radiation kills the cells.

Thus far, the most successful use for buckyballs is in the realm of superconductors. In a conductor, such as copper wire, an electric current quickly diminishes due to internal resistance. Superconductors allow a current to flow indefinitely because their resistance is nearly zero. In 1911, Dutch physicist Heike Onnes was able to get a copper wire to exhibit superconductivity when immersed in liquid helium at 4 Kelvin (4 K). Absolute zero (0 K) is the point at which all molecular motion ceases. It is extremely difficult to work at the temperature of liquid helium so researchers turned to buckyballs to see if they would exhibit superconductivity at higher temperatures.

The first report in 1991 cited success at 18 K and periodically new papers have pushed the temperature ever higher. The latest, reported by Robert Service in the Aug. 31 issue of Science, says that buckyballs have been made to superconduct at 117 K. This is 40 degrees warmer than the temperature of liquid nitrogen (77 K), a material that is both easy to manipulate and relatively cheap. This success is leading to hopes that a room temperature superconductor may not lie too far in the future.

Clair Wood taught physics and chemistry for more than a decade at Eastern Maine Technical College in Bangor.