Jakub Ossowski oral presentation (OB2-Mon1-2-1)
Thiolate versus Selenolate: Molecule-substrate interface analysis in aromatic self-assembled monolayers by S-SIMS and TP-SIMS.
1 Jagiellonian University, Lojasiewicza 11, 30-348 Krakow, Poland
2 Goethe University, Max-von-Laue 7, 60438 Frankfurt, Germany
Self-assembled monolayers (SAMs) are considered one of the most prototypical system for investigating physical and chemical properties of organic nanostructures and their potential application in nanotechnology. The key element in this type of material is chemical bonding between molecules and substrate, which has crucial influence on the stability of the entire monolayer.
Most of the studies of SAMs have been performed using S-Au bonding. More recently the Se-Au bonding is considered as an interesting alternative, however there is still missing information which of these head group provides higher stability binding to the Au(111) substrate. A meaningful comparison of S-Au and Se-Au stability requires that respective molecules not only have the same carbon backbones, but also should form ordered structures with very similar molecular packing. Only under such conditions, not fulfilled by the most of previous studies, the contribution of the molecule-substrate bonding on the film stability can be elucidated. Following this idea, we will present data obtained for naphthalene based SAMs bound to the Au(111) substrate via S or Se atoms.1 Microscopic and spectroscopic characterization of these SAMs reveals formation of very similar well-ordered structures, for which analysis of the molecule-metal interface stability is possible.1 In the talk we will discuss first static-SIMS (S-SIMS) measurements and correlate obtained data with the exchange experiments to analyze stability of chemical bonding at the molecule-metal interface.1 In the second part we will compare thermal stability of both types of SAMs in a range of 300-750K using temperature-programmed SIMS (TP-SIMS).2 Combination of S-SIMS and TP-SIMS experiments demonstrates higher stability of surface bonding in the case the selenolates with at the same lower thermal stability of this systems as compared to thiols. Simple explanation of this seemingly contradicting result will be provided on the basis of SIMS experiments.2
 Ossowski et al. ACS Nano 2015, 9, 4508-4526
 Ossowski et al. 2017 in preparation.