Non-thermal desorption/ablation of molecular solids induced by ultra-short soft x-ray pulses
2009 (English)In: Optics Express, ISSN 1094-4087, Vol. 17, no 1, 208-217 p.Article in journal (Refereed) Published
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 21.7nm, 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 32nm. 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 hardening making the beam profile measurement infeasible. (C) 2008 Optical Society of America
Place, publisher, year, edition, pages
2009. Vol. 17, no 1, 208-217 p.
IdentifiersURN: urn:nbn:se:uu:diva-129260ISI: 000262220300024OAI: oai:DiVA.org:uu-129260DiVA: diva2:338139