Dresden 2011 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 31: Postersitzung II

MM 31.40: Poster

Mittwoch, 16. März 2011, 17:15–18:45, P5

Laser-assisted atom probe tomography of self-organized surface layers — •Andreas Stoffers and Guido Schmitz — Institut für Materialphysik, Westf. Wilhelms-Universität, Wilhelm-Klemm-Strasse 10, 48149 Münster, Germany

The availability of femtosecond lasers facilitates the analysis of new material classes by atom probe tomography. Pulsed-laser atom probe tomography (PLAP) has the potential to give even structural and chemical information of biological and organic materials at an atomic scale. In order to explore the possibilities of analyzing nanometric materials, we have chosen the model cases of polyelectrolyte multilayers (PEM) and self assembled monolayers (SAM). PEMs are adsorbed step by step as a multilayer of poly-anions and poly-cations at the apex of sharp gold tips. SAMs are also adsorbed in a self-assembling process at the apex of sharp gold tips, but offer only a limited volume for analysis. By means of laser-assistance it is indeed possible to chemically analyze different PEMs and SAMs. In all cases the mass spectra are complex, characterized by peaks of multiple fractions of different molecular mass. Since these molecular species are very similar for the studied polymer types, it is hard to distinguish the organic molecules from the time-of-flight spectrum. However, different polymer-types might be distinguished based on the intensity ratio between characteristic mass peaks. In addition, a 3D reconstruction of a fluorinated SAM will be presented to demonstrate the ability of getting structural information of the alignment and distribution of the oligomeres.