Microscopic kinetics in poly(Methyl methacrylate) exposed to a single ultra-short xuv/x-ray laser pulse

0548840 - ÚFP 2022 RIV CH eng J - Článek v odborném periodiku
Medvedev, Nikita - Chalupský, J. - Juha, L.
Microscopic kinetics in poly(Methyl methacrylate) exposed to a single ultra-short xuv/x-ray laser pulse.
Molecules. Roč. 26, č. 21 (2021), č. článku 6701. E-ISSN 1420-3049
Grant CEP: GA MŠMT LTT17015
Institucionální podpora: RVO:61389021
Klíčová slova: Ablation * Band gap collapse * Free-electron laser * Nonthermal melting * pmma
Obor OECD: Optics (including laser optics and quantum optics)
Impakt faktor: 4.927, rok: 2021
Způsob publikování: Open access
https://www.mdpi.com/1420-3049/26/21/6701

We study the behavior of poly(methyl methacrylate) (PMMA) exposed to femtosecond pulses of extreme ultraviolet and X-ray laser radiation in the single-shot damage regime. The employed microscopic simulation traces induced electron cascades, the thermal energy exchange of electrons with atoms, nonthermal modification of the interatomic potential, and a triggered atomic response. We identify that the nonthermal hydrogen decoupling triggers ultrafast fragmentation of PMMA strains at the absorbed threshold dose of ~0.07 eV/atom. At higher doses, more hydrogen atoms detach from their parental molecules, which, at the dose of ~0.5 eV/atom, leads to a complete separation of hydrogens from carbon and oxygen atoms and fragmentation of MMA molecules. At the dose of ~0.7 eV/atom, the band gap completely collapses indicating that a metallic liquid is formed with complete atomic disorder. An estimated single-shot ablation threshold and a crater depth as functions of fluence agree well with the experimental data collected.
Trvalý link: http://hdl.handle.net/11104/0324888