Paper TF-WeA4
Probing Stability of the Molecule-Substrate Interface in Self-Assembled Monolayers by Ion-Beam-Induced Desorption

Wednesday, October 20, 2010, 3:00 pm, Room Pecos

Due to the ease of preparation and their relatively high stability, self-assembled monolayers (SAMs) are very promising candidates to be used in the development of micro- and nano-structured materials. With numerous detailed studies available nowadays for SAMs, the identification of SAMs adsorption geometry and stability of molecule-substrate interface still remains controversial and rather difficult to access experimentally. In this presentation we report experiments on ion-induced desorption and resonance enhanced ionization mass spectrometry of SAMs on Au(111) substrate.¹ Althrough ion-induced desorption is commonly considered as a very invasive process when used for probing monomolecular films, our experiments demonstrate that this method can be successfully applied to monitor fine changes in the molecule-substrate interface stability of model SAMs systems based on thiols ( CH₃‑C₆H₄‑C₆H₄-(CH₂)_n-S-Au(111), n = 2-6) and selenols (BPnSe, CH₃‑C₆H₄‑C₆H₄-(CH₂)_n-Se-Au(111), n = 2-6) . Current desorption experiments will be discussed together with recent microscopic² and spectroscopic³ analysis of the molecular structure and stability of these SAMs. We demonstrate that lower or higher ion-induced bond scission efficiency can be correlated with, respectively, higher or lower chemical stability of particular chemical bonds. Thus, a new method for probing the stability of the substrate-SAM interface can be proposed.

References

(1) S. Wyczawska, F. Vervaecke, et al. in preparation.

(2) P. Cyganik, K. Szelagowska-Kunstman, et al. J. Phys. Chem. C 2008, 112, 15466.

(3) K. Szelagowska-Kunstman, P. Cyganik, et al. Phys. Chem. Chem. Phys. 2010, 12, 4400.