What did Ertl do to win his Nobel Prize?
Ertl helped transform surface chemistry into its modern form, showing that you could work out how molecules were moving, step by step, on the surface of a solid. Before the 1960s, it was impossible to form a picture of exactly what molecules were doing at surfaces, though they were already used industrially to speed up many reactions. Over a lifetime, Ertl helped explain the mystery behind this black box. He prepared clean metal surfaces in almost perfect vacuum and slowly injected gas molecules onto them. Though the molecules couldn’t be seen, it was possible to work out their behaviour by firing electrons, x-rays, and ultraviolet and infrared rays at them. The rays would bounce off, diffract, or knock out electrons – taken together, this evidence allowed Ertl to explain what was going on when nitrogen and hydrogen reacted on iron, or when carbon monoxide turns into carbon dioxide on the surface of platinum, for example. He picked his way through a formidable series of methods to a co
