Sir Harold W. Kroto

Sir Harold W. Kroto, born in 1939, British chemist and Nobel laureate. Kroto’s inquiry into the origins of carbon produced by stars led to the accidental discovery of a new family of carbon molecules known as fullerenes (see Buckminsterfullerene). Unknown before 1985, fullerenes now constitute the fourth major form of carbon, along with graphite, diamond, and amorphous carbon. The discovery and synthesis of fullerenes created a new and extremely active branch of chemistry in the early 1990s.

Kroto was born in Wisbech in Cambridgeshire, England. He earned his undergraduate degree in chemistry in 1961 and his Ph.D. degree in chemistry in 1964, both from the University of Sheffield. After three years of postdoctoral research in Canada and the United States, Kroto joined the faculty of the University of Sussex, becoming a professor in 1985. In 1991 he was made Royal Society Research Professor.

Throughout the 1970s Kroto’s area of concentration was microwave spectroscopy. He used radio astronomy to capture and analyze traces of molecules produced in interstellar space. In particular, he was intrigued by his detection of long-chained molecules of carbon and nitrogen. Kroto surmised that these chains are formed in the atmospheres of carbon-rich giant stars called carbon stars; what he needed was a way of mimicking the conditions under which the chains are created.

The answer was found at Rice University in Houston, Texas, where Kroto’s acquaintance Robert F. Curl, Jr., along with another Rice professor, Richard E. Smalley, were conducting research in cluster chemistry. Using a specialized laser that Smalley had designed, the Rice chemists were vaporizing substances and creating clusters—tiny formations of atoms that could be analyzed.

In September 1985 Kroto traveled to Houston. Over an 11-day period, Kroto, Smalley, and Curl, with graduate students James R. Heath and Sean C. O’Brien, created carbon clusters. Smalley’s laser blasted carbon atoms from graphite, mixing them with the inert gas helium and cooling the mixture in a vacuum chamber. Examining the minuscule clusters, the team had a surprise: Instead of the long chains they expected, they found evidence of closed, symmetrical, cagelike arrangements of carbon atoms, with a 60-atom structure being the most abundant.

Ultimately, the team theorized that the new C₆₀ molecule’s structure resembled that of a soccer ball. The structure also resembled the geodesic domes designed by American architect R. Buckminster Fuller. Kroto and his colleagues dubbed the molecules buckminsterfullerene, or buckyballs for short.

The team published the results of their work in late 1985, presenting their hypothesis of a brand-new family of sphere-shaped carbon molecules, but many scientists were skeptical. Kroto returned to England, working on a way to synthesize large quantities of the molecules now known as fullerenes. He and colleagues successfully developed a method in 1990, but they were dismayed when another team announced its own method, beating Kroto’s team to publication by only days. Nevertheless, the structure of fullerenes was confirmed, and the field of fullerene chemistry exploded almost overnight.

Chemists have now developed thousands of fullerene variations, including sturdy tubelike and wirelike structures of fullerenes that can be made to carry other atoms, bringing the promise of important applications in industry and biomedicine. For their discovery, Kroto, Smalley, and Curl shared the 1996 Nobel Prize in chemistry. Kroto was knighted in 1996.