Locally induced co-adsorption results in the growth of adjacent domains of different compounds.

The approach is based on three subsequent steps: Initially, a monolayer is grown via OSWD using nanocrystals of one compound suspended withing a viscous matrix. Secondly, the STM tip is dip-coated with a suspension of nanocrystals of another compound. Then, the coated tip is penetrated through the substrate- supported suspension of the first compound in order to encounter the substrate surface. After a short and slight physical contact of the tip with the substrate, the tip is retracted to the imaging mode distance. Images following this procecure show that a domain of the tip-coating compound has grown in the area of contact within the initial monolayer.

Our dip-pen approach contributes to the set of coadsorption strategies such as host-guest self-assembly or the growth of noncovalently bound complexes. In contrast to these approaches, which create uniform monolayers from mixed solutions, dip-pen STM coadsorption can be achieved at predefined sites locally at the nanoscale, thus enabling to generate monolayers doped with chemically different domains.

---

Publication:

Various approaches to control solid/solid wetting self-assembly of organic semiconductors with STM.
F. Trixler, W.M. Heckl, In: Mendez-Vilas, A.; Diaz, J. (Eds.):
Modern Research and Educational Topics in Microscopy (2), 534-541. Formatex, Badajoz (2007).
ISBN: 978-84-611-9420-9.