Article published in Nanoscale Horizons by Fernando Martín, Amadeo L. Vázquez de Parga, IFIMAC researchers.
In the 90’s a theoretical study proposed the idea that the existence of surface localized photoelectrons can be relevant for on-surface photochemistry of diatomic molecules. In this work we show that the same idea is extensible to long chain molecules where the affinity levels of the molecules are more delocalized. We focus our study on long-chain acenes due to their interesting electronic properties. These molecules have been proposed for carbon-based spintronics or electronic applications for their semiconductor properties. In general, they are difficult to synthesize due to their low solubility and high reactivity. We have deposited α-bisdiketone precursors on graphene grown epitaxially on Ru(0001). The interaction between graphene and Ru(0001) creates a surface resonance that coincides in energy with the n-π* transition of the diketone group. The photoelectrons produced on the Ru(0001) substrate exposing to visible light populate the surface state and are easily transferred by inelastic scattering to the affinity levels of the precursors. The conversion yield is much higher than in other substrates that do not present an unoccupied surface state. These results allow the design of surfaces to improve the efficiency in photochemistry processes opening the door to the efficient synthesis of complex molecules on surfaces. [Full article]