Dresden 2017 – scientific programme

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O: Fachverband Oberflächenphysik

O 85: Thin Films, Nanostructures and Nanoparticles I

O 85.10: Talk

Thursday, March 23, 2017, 12:45–13:00, ZEU 114

An in-situ STXM approach to understand soft x-ray induced chemical modification in polymers — •Markus Meyer¹, Andreas Späth¹, Benjamin Watts², and Rainer H. Fink¹ — ¹Friedrich-Alexander Universität Erlangen-Nürnberg, Physikalische Chemie II, Erlangen, Germany — ²SwissLight Source (SLS), Paul Scherrer Institut, Villigen, Switzerland

Certain binding motifs in organic molecules are very sensitive to UV or XUV irradiation which induces severe chemical modifications. Scanning transmission x-ray microspectroscopy (STXM) was used to follow the evolution of effects like mass loss (due to bond rupture) and chemical changes of sample in an all but in-situ fashion. In our studies we investigated carbonyl group containing ultrathin free-standing films of PMMA, PLA and polycarbonate. The aim is a comprehensive study on x-ray induced chemical modification of the target for resonant and non-resonant excitations. It is found that the cleavage of chemical bonds does not follow a defined reaction pathway, thus directly leading to the formation of new C=C double bonds. In contrary, our studies provide clear evidence of small molecule fragments leaving the sample, thereby changing the chemical nature of the pristine material. This process is accompanied by deposition of residual gas onto the sample of interest as an unavoidable secondary process. Theoretical considerations are applied in a simulation and are able to retrace and to confirm the findings of the in-situ STXM analysis going well beyond recent publications [1]. [1] Leontowich, A. et al, JElectronSpectrosc, 58-64, 206, 2016