Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 47: Poster: Interfaces and Thin Films

CPP 47.19: Poster

Mittwoch, 9. März 2016, 18:15–21:00, Poster B2

Dose and energy dependent chemical modification of ultrathin polymer films as studied by STXM — Markus Meyer¹, Andreas Späth¹, Benjamin Watts², and •Rainer H. Fink¹ — ¹FAU Erlangen-Nürnberg, PC II, Erlangen, Germany — ²SwissLight Source, Paul Scherrer Institut, Villigen, Switzerland

Organic molecules are very sensitive to intense UV or XUV irradiation which may induce severe chemical modifications. We have employed scanning transmission x-ray microspectroscopy to investigate the influences of photon energy, photon flux and illumination sequence (for different energies) to explore effects like mass loss (due to bond rupture) or chemical changes. In our studies we investigate ultrathin free-standing films of poly-methyle methacrylate (PMMA), polylactic acid (PLA) and polystyrene (PS). The aims specifically focus on the impact of secondary electrons after near-threshold, on-resonance and high-energy irradiation (30 or 100 eV above resonance). It is found that the absorbed dose as a common criterion for induced damage does not necessarily correlate with the observed chemical damage. We conclude a destabilization of respective bonds due to resonant excitation, thus resulting in a higher probability of subsequent bond cleavage and simultaneous formation of new species. Kinetic studies comparing resonant and non-resonant excitations and degradation processes of the chemical structure complete the studies. Profound understanding of mechanisms in the interplay of irradiation with soft matter, allow to prevent and avoid sample degradation and in particular cases take advantage of the introduced, controlled chemical modification.