title: Non-thermal desorption/ablation of molecular solids induced by ultra-short soft x-ray pulses.
abstract: We report the first observation of single-shot soft x-ray laser induced desorption occurring below the ablation threshold in a thin layer of poly (methyl methacrylate)--PMMA. Irradiated by the focused beam from the Free-electron LASer in Hamburg (FLASH) at 21.7 nm, the samples have been investigated by atomic-force microscope (AFM) enabling the visualization of mild surface modifications caused by the desorption. A model describing non-thermal desorption and ablation has been developed and used to analyze single-shot imprints in PMMA. An intermediate regime of materials removal has been found, confirming model predictions. We also report below-threshold multiple-shot desorption of PMMA induced by high-order harmonics (HOH) at 32 nm. Short-time exposure imprints provide sufficient information about transverse beam profile in HOH's tight focus whereas long-time exposed PMMA exhibits radiation-initiated surface ardening making the beam profile measurement infeasible.
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Prague 8, Czech Republic. chal@fzu.cz
authors.forename: J
authors.initials: J
authors.lastname: Chalupský
authors.forename: L
authors.initials: L
authors.lastname: Juha
authors.forename: V
authors.initials: V
authors.lastname: Hájková
authors.forename: J
authors.initials: J
authors.lastname: Cihelka
authors.forename: L
authors.initials: L
authors.lastname: Vysín
authors.forename: J
authors.initials: J
authors.lastname: Gautier
authors.forename: J
authors.initials: J
authors.lastname: Hajdu
authors.forename: S P
authors.initials: SP
authors.lastname: Hau-Riege
authors.forename: M
authors.initials: M
authors.lastname: Jurek
authors.forename: J
authors.initials: J
authors.lastname: Krzywinski
authors.forename: R A
authors.initials: RA
authors.lastname: London
authors.forename: E
authors.initials: E
authors.lastname: Papalazarou
authors.forename: J B
authors.initials: JB
authors.lastname: Pelka
authors.forename: G
authors.initials: G
authors.lastname: Rey
authors.forename: S
authors.initials: S
authors.lastname: Sebban
authors.forename: R
authors.initials: R
authors.lastname: Sobierajski
authors.forename: N
authors.initials: N
authors.lastname: Stojanovic
authors.forename: K
authors.initials: K
authors.lastname: Tiedtke
authors.forename: S
authors.initials: S
authors.lastname: Toleikis
authors.forename: T
authors.initials: T
authors.lastname: Tschentscher
authors.forename: C
authors.initials: C
authors.lastname: Valentin
authors.forename: H
authors.initials: H
authors.lastname: Wabnitz
authors.forename: P
authors.initials: P
authors.lastname: Zeitoun
mesh_terms: D001896:Boron Compounds / Q000528:radiation effects; D002244:Carbon / Q000528:radiation effects; D004583:Electrons; D053685:Laser Therapy / Q000379:methods; D007834:Lasers; D018625:Microscopy, Atomic Force; D019904:Polymethyl Methacrylate; D013053:Spectrophotometry; D013499:Surface Properties; D014466:Ultraviolet Rays; D014965:X-Rays
chemical_list: D001896:Boron Compounds; D002244:Carbon; D019904:Polymethyl Methacrylate