"On-surface synthesis: What happens behind the scenes?"
Marco Di Giovannantonio
CNR - Institute of Structure of Matter, via Fosso del Cavaliere 100, 00133 Roma (Italy)
The fabrication of technologically-relevant, carbon-based nanomaterials with atomic precision mainly relies on the on-surface synthesis approach. Carefully designed molecular building blocks are deposited on atomically flat surfaces and the promotion of intra and intermolecular chemical reactions leads to the achievement of the desired products. The confinement in two dimensions allows using the wide characterization toolkit of the surface science, unveiling physical and chemical properties down to the atomic scale.
Two main aspects represent the drive toward deep understanding of on-surface phenomena and fine-tuning of low-dimensional nanostructures in a controlled manner: (i) the discovery of new, selective on-surface chemical reactions, and (ii) the establishment of investigation tools able to dynamically capture key information of the ongoing processes.
In this talk, I will address these two aspects by showing some related case studies. First, I will report on the use of methyl, vinyl and isopropyl groups as the smallest carbon-based tools to modify the architecture of organic nanostructures and promote novel synthetic pathways. Experimentally, these studies are conducted in ultrahigh vacuum via scanning tunneling microscopy and noncontact atomic force microscopy with CO-functionalized tips, complemented by density-functional theory calculations. Afterwards, I will discuss the monitoring of dynamic processes in the on-surface growth of organic nanomaterials via the use of temperature-programmed x-ray photoelectron spectroscopy (with synchrotron radiation), to track surface-confined reactions and disclose their mechanistic details.