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O: Fachverband Oberflächenphysik

O 66: Oxide Surfaces II

O 66.6: Vortrag

Donnerstag, 14. März 2013, 11:45–12:00, H42

Boron nitride as a template for molecular adsorption, self-assembly and electronic decoupling of the prototype macrocycle porphine. — •Felix Bischoff, Sushobhan Joshi, Knud Seufert, David Ecija, Saranyan Vijayaraghavan, Willi Auwärter, and Johannes Barth — Physik Department E20, TUM, James Franck Str. 1, 85748 Garching, Germany

Motivated by its bulk and thin film properties and successful incorporation into graphene nanodevices, boron nitride (BN) has gained great attention. Recently, a vapor-deposited BN monolayer on a Cu support was comprehensively characterized [1]. It is topographically smooth, yet electronically patterned and therefore provides a versatile template for molecular adsorption, self-assembly and electronic decoupling of molecular nanosystems. In this work, these properties are exemplified by systematic STM and STS experiments. The macrocyclic model compound porphine (2H-P) does not spontaneously form ordered structures on bare Cu at room temperature due to strong substrate-adsorbate interactions. However, a BN spacer layer electronically decouples these molecules and enables 2-D self-assembly. It also serves as an electronic template due to variations in its potential landscape and traps 2H-P at specific sites. At low- and intermediate coverages, arrays of well-separated, but highly-ordered porphine islands are observed, following the BN moiré structure. The inhomogenous BN template also dictates the electronic level alignment, as evidenced by a spatial modulation of the energy of porphine frontier orbitals.

[1] Joshi et al., Nano Lett., 2012, 12 (11), pp 5821-5828