An ordinary octane molecule is a chain of eight carbon atoms, like a flexible wire. On a hot platinum surface (above 600 K), it doesn't just lie still: it starts to squirm. First, the chain bends so that its ends come closer together. Then hydrogen atoms are stripped off, and a strong bond forms between the ends — the molecule closes into a hexagonal benzene ring. This transformation is called aromatization: a flexible chain becomes a rigid, flat ring.

Sometimes two octane molecules lie side by side. Then platinum stitches their ends together, and the bond propagates along both chains like a zipper. The result is a long double molecule that can fold into more complex structures. This is how polycyclic compounds (the basis of many dyes, drugs, and plastics) are born on the surface.