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arXiv · 1712.02115

Contrasting behavior of covalent and molecular carbon allotropes exposed to extreme ultraviolet and soft x-ray free-electron laser radiation

M. Toufarová·V. Hájková·J. Chalupský·T. Burian·J. Vacík·V. Vorlíček·L. Vyšín·J. Gaudin·N. Medvedev·B. Ziaja·M. Nagasono·M. Yabashi·R. Sobierajski·J. Krzywinski·H. Sinn·M. Störmer·K. Koláček·K. Tiedtke·S. Toleikis·L. Juha
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Abstract

All carbon materials, e.g., amorphous carbon (a-C) coatings and C60 fullerene thin films, play an important role in short-wavelength free-electron laser (FEL) research motivated by FEL optics development and prospective nanotechnology applications. Responses of a-C and C60 layers to the extreme ultraviolet (SPring-8 Compact SASE Source in Japan) and soft x-ray (free-electron laser in Hamburg) free-electron laser radiation are investigated by Raman spectroscopy, differential interference contrast, and atomic force microscopy. A remarkable difference in the behavior of covalent (a-C) and molecular (C60) carbonaceous solids is demonstrated under these irradiation conditions. Low thresholds for ablation of a fullerene crystal (estimated to be around 0.15 eV/atom for C60 vs 0.9 eV/atom for a-C in terms of the absorbed dose) are caused by a low cohesive energy of fullerene crystals. An efficient mechanism of the removal of intact C60 molecules from the irradiated crystal due to Coulomb repulsion of fullerene-cage cation radicals formed by the ionizing radiation is revealed by a detailed modeling.

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M. Toufarová, V. Hájková, J. Chalupský, T. Burian, J. Vacík, V. Vorlíček, L. Vyšín, J. Gaudin, N. Medvedev, B. Ziaja, M. Nagasono, M. Yabashi, R. Sobierajski, J. Krzywinski, H. Sinn, M. Störmer, K. Koláček, K. Tiedtke, S. Toleikis, L. Juha. 2017-12-06. Contrasting behavior of covalent and molecular carbon allotropes exposed to extreme ultraviolet and soft x-ray free-electron laser radiation. https://doi.org/10.1103/physrevb.96.214101

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