The thermally-induced polymerization of α-sexithiophene (6T) molecules on Ag(001) and Au(001) gives rise to long unbranched polymer chains or branched polymer networks depending on the annealing parameters. There, the onset temperature for polymerization depends on the strength of interaction with the underlying substrate. Similar polymerization processes are also induced by ultraviolet radiation with photon energies between 3.0 and 4.2 eV. Radical formation by an electronic excitation in the 6T molecule is proposed as the driving mechanism that necessitates the interplay with the metallic substrate.

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