Measured and theoretically simulated images of stages in the dehydrogenation process observed in programmed surface heating experiments. The sequence starts from adsorbed ethene (at 300K), leading to self-evolved 24-carbon-atom cluster precursors (between 570K and 670 K), and culminates with graphene formed at elevated temperatures (between 770K and 970K). (Figure credit: U. Landman and B. Yoon).