Now that's a birthday present! Instead of receiving the random necktie on his 71st birthday today, this morning Gerhard Ertl was awarded this year's Nobel Prize in Chemistry. Ertl, a physical chemist at the Fritz-Haber Institute of the Max Planck Society in Berlin, Germany, won for developing modern methods that reveal how chemical reactions take place on metals and other surfaces. Those techniques have led to everything from the development of catalysts that remove poisonous carbon monoxide from car exhaust to the understanding of how ice crystals in stratospheric clouds supercharge atmospheric chlorine's ability to destroy the planet's protective ozone layer.
"This is really well-deserved," says Ralph Nuzzo, a surface chemist at the University of Illinois, Urbana-Champaign. "Ertl is a titan," Nuzzo says. "The reactions occurring at surfaces are very difficult to probe because there are so few molecules involved, and they frequently occur very rapidly," adds John Vickerman, a chemist at the University of Manchester in the U.K. "Furthermore, the scientist has to distinguish what is happening in a layer one molecule thick from the rest of the solid. Ertl developed very sophisticated physical tools to identify the chemistry occurring at the surface." According to the Royal Swedish Academy of Sciences, which awards the Nobel Prizes, Ertl was selected not so much for the development of any particular tool, technique, or discovery, as is often the case, but because "he established an experimental school of thought for the entire discipline."
One famous example was in figuring out how iron-based catalysts convert hydrogen and nitrogen into ammonia, a critical industrial process for making artificial fertilizers that remain the basis for modern agriculture. This conversion, known as the Haber-Bosch process, combines dinitrogen molecules from the air with dihydrogen molecules. Earlier studies had revealed that the slowest step in the process was nitrogen molecules adsorbing onto iron particles in a manner that primed them for combining with hydrogen. The triple bond shared by these nitrogens is one of the strongest in chemistry. And researchers didn't know if the nitrogen molecules first broke apart before reacting with hydrogen or reacted as intact molecules. By systematically using an array of spectroscopic techniques and other tools, Ertl was able to reveal the complete 7-step process whereby nitrogen and hydrogen molecules land on an iron surface, break apart, and react to form ammonia.
After receiving the announcement earlier today, about 200 of Ertl's colleagues toasted him with champagne and German pretzels on the shaded lawn of the Fritz-Haber Institute. After Ertl fielded a few questions from TV reporters, the crowd broke out in a rousing round of "Happy Birthday."
In an earlier phone interview with ScienceNOW, Ertl was quick to offer credit to his colleagues in the field. The field, he says, was propelled by the parallel development of many surface characterization techniques. And, he adds, that many scientists were adept at applying them, such as Gabor Somorjai, with whom he shared the 1998 Wolf Prize in Chemistry for their work in surface science. "I was a little bit disappointed he didn't share [the Nobel Prize] with me," Ertl says. But then again, his birthday is 4 May.