Similarity in ruthenium damage induced by photons with different energies: From visible light to hard X-rays

I. Milov*, V. Lipp, D. Ilnitsky, N. Medvedev, K. Migdal, V. Zhakhovsky, V. Khokhlov, Yu Petrov, N. Inogamov, S. Semin, A. Kimel, B. Ziaja, I. A. Makhotkin, E. Louis, F. Bijkerk

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)
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Abstract

We performed combined experimental and computational research on damage processes in ruthenium thin films induced by femtosecond lasers with various photon energies. We present an experiment with an optical laser at normal incidence conditions and compare it with previously reported experiments at grazing incidence conditions with XUV and hard X-ray photons, covering a large range of photon energies. Analysis of ablation craters in Ru shows very similar crater morphology and depth of about 10–20 nm for all considered irradiation conditions. Simulations of light-matter interactions are performed with our combined Monte Carlo and two-temperature hydrodynamics approach. The simulation results show that the primal cause of eventual ablation is Auger decay of core-shell holes created after absorption of XUV and hard X-ray photons in the vicinity of ruthenium surface. They lead to the creation of many low-energy electrons which consequently release the absorbed energy near the surface, resembling the optical irradiation case. Similar absorbed energy distributions in the top part of ruthenium induce a similar thermo-mechanical response and, therefore, similar ablation process. Our results suggest that such mechanism is universal in a wide range of photon energies at grazing incidence conditions, when the photon absorption depth is smaller than the photoelectrons range.

Original languageEnglish
Article number143973
JournalApplied surface science
Volume501
DOIs
Publication statusPublished - 31 Jan 2020

Keywords

  • Extreme ultraviolet
  • Femtosecond laser ablation
  • Monte Carlo simulations
  • Thin films
  • Two-temperature hydrodynamics
  • X-ray free electron lasers

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