Tip-induced chemistry

On-surface synthesis under ultra-high vacuum conditions has made remarkable progress over the last two decades. Two main strategies can be distinguished: On one side, using thermal activation (or global exposure to light) and on the other side, using atom manipulation. Both have strengths and weaknesses. With thermal activation, many product molecules are formed in parallel and with typically high yield [1, 2]. In contrast, atom manipulation [3], in the context of molecules called tip-induced chemistry [4, 5], requires each molecule to be generated individually. One advantage of this approach is the ability to form highly reactive and out-of-equilibrium products. Moreover, tip-induced chemistry potentially allows the creation of complex, individual and custom-designed nanostructures [6]. Both techniques can be efficiently combined by using tip-induced chemistry to modify structures that were synthesized by thermal activation.