The on-surface photogeneration of nonacene from α-bisdiketone precursors deposited on nanostructured epitaxial graphene grown on Ru(0001) has been studied by means of low temperature scanning tunneling microscopy and spectroscopy. The presence of an unoccupied surface state, spatially localized in the regions where the precursors are adsorbed, and energetically accessible in the region of the electromagnetic spectrum where n–π* transitions take place, allows for a 100% conversion of the precursors into nonacenes. With the help of state-of-the-art theoretical calculations, we show that such a high yield is due to the effective population of the surface state by the incoming light and the ensuing electron transfer to the unoccupied states of the precursors through an inelastic scattering mechanism. Our findings are the experimental confirmation that surface states can play a prominent role in the surface photochemistry of complex molecular systems, in accordance with early theoretical predictions made on small molecules.

中文翻译：

---

九苯在纳米结构石墨烯上的高效光生

已经通过低温扫描隧道显微镜和光谱学研究了从沉积在 Ru(0001) 上生长的纳米结构外延石墨烯上的 α-双二酮前体在表面光生九苯。未占据的表面态的存在，在空间上定位在吸附前体的区域，并且在发生 n-π* 跃迁的电磁光谱区域中能量可及，允许前体 100% 转化为九并苯。在最先进的理论计算的帮助下，我们表明如此高的产率是由于入射光的表面状态的有效种群以及随后的电子通过非弹性转移到前体的未占据状态散射机制。