Chemical syntheses in liquids and gases take place in three-dimensional space. Random collisions between molecules have to result in something new in an extremely short time. But there is another way: on a gold surface under ultrahigh vacuum conditions, molecules lying still next to each other can be made to combine - even those that would never 'want' to react with each other in a liquid. Researchers have now discovered such a reaction. Best of all, the experts can 'take pictures' and watch every step of the reaction.