Damage accumulation in thin ruthenium films induced by repetitive exposure to femtosecond XUV pulses below the single-shot ablation threshold

Makhotkin, Igor A.; Milov, Igor; Chalupský, J.; Tiedtke, K.; Enkisch, H.; Vries, Gosse de; Scholze, Frank; Siewert, Frank; Sturm, Jacobus Marinus; Nikolaev, K. V.; Kruijs, R. W. E. van de; Smithers, M.A.; Wolferen, H.A.G.M. van; Keim, Enrico G.; Louis, Eric; Jacyna, Iwanna; Jurek, M.; Klinger, D.; Pełka, J.; Juha, L.; Hájková, V.; Vozda, Vojtěch; Burian, T.; Saksl, K.; Faatz, B.; Keitel, Barbara; Plönjes, Elke; Schreiber, S.; Toleikis, S.; Loch, R.A.; Hermann, Martin; Strobel, Sebastian; Donker, Rilpho; Mey, Tobias; Sobierajski, R.

doi:10.1364/josab.35.002799

Cited by 7 publications

(1 citation statement)

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“…In our previous studies we focused on severe damage of Ru thin films in single- [14,15,16] and multi-shot regimes [17], as well as on a longterm exposure of Ru at fluences significantly below the single-shot ablation threshold [18]. Such sub-threshold investigation of material degradation is challenging since the processes involved are elusive to be detected postmortem.…”

Section: Introductionmentioning

confidence: 99%

Laser-induced electron dynamics and surface modification in ruthenium thin films

Akhmetov¹,

Milov²,

Semin³

et al. 2022

Preprint

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We performed the experimental and theoretical study of the heating and damaging of ruthenium thin films induced by femtosecond laser irradiation. Results of an optical pump-probe thermoreflectance experiment with rotating sample allowing to significantly reduce heat accumulation in irradiated spot are presented. We show the evolution of surface morphology from growth of a heat-induced oxide layer at low and intermediate laser fluences to cracking and grooving at high fluences. Theoretical analysis of pumpprobe signal allows us to relate behavior of hot electrons in ruthenium to the Fermi smearing mechanism. The analysis of heating is performed with the two-temperature modeling and molecular dynamics simulation, results of which demonstrate that the calculated melting threshold is higher than experimental damage threshold. We attribute it to heat-induced surface stresses leading to cracking which accumulates to more severe damage morphology. Our results provide an upper limit for operational conditions for ruthenium optics and also direct to further studies of the Fermi smearing mechanism in other transition metals.

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