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Desorption/ablation of lithium fluoride induced by extreme ultraviolet laser radiation

Blejchař T., Nevrlý V., Vašinek M., Dostál M., Kozubková M., Dlabka J., Stachoň M., Juha L., Bitala P., Zelinger Z., Pira P., Wild J.

Nukleonika

2016

Vol. 61, No. 2

131--138

The availability of reliable modeling tools and input data required for the prediction of surface removal rate from the lithium fluoridetargets irradiated by the intense photon beams is essential for many practical aspects. This study is motivated by the practical implementation of soft X-ray (SXR) or extreme ultraviolet (XUV) lasers for the pulsed ablation and thin fi lm deposition. Specifically, it is focused on quantitative description of XUV laser-induced desorption/ablation from lithium fluoride, which is a reference large band-gap dielectric material with ionic crystalline structure. Computational framework was proposed and employed here for the reconstruction of plume expansion dynamics induced by the irradiation of lithium fluoridetargets. The morphology of experimentally observed desorption/ablation craters were reproduced using idealized representation (two-zone approximation) of the laser fluence profile. The calculation of desorption/ablation rate was performed using one-dimensional thermomechanic model (XUV-ABLATOR code) taking into account laser heating and surface evaporation of the lithium fluoridetarget occurring on a nanosecond timescale. This step was followed by the application of two-dimensional hydrodynamic solver for description of laser-produced plasma plume expansion dynamics. The calculated plume lengths determined by numerical simulations were compared with a simple adiabatic expansion (blast-wave) model. The availability of reliable modeling tools and input data required for the prediction of surface removal rate from the lithium fluoridetargets irradiated by the intense photon beams is essential for many practical aspects. This study is motivated by the practical implementation of soft X-ray (SXR) or extreme ultraviolet (XUV) lasers for the pulsed ablation and thin fi lm deposition. Specifically, it is focused on quantitative description of XUV laser-induced desorption/ablation from lithium fluoride, which is a reference large band-gap dielectric material with ionic crystalline structure. Computational framework was proposed and employed here for the reconstruction of plume expansion dynamics induced by the irradiation of lithium fluoridetargets. The morphology of experimentally observed desorption/ablation craters were reproduced using idealized representation (two-zone approximation) of the laser fluence profile. The calculation of desorption/ablation rate was performed using one-dimensional thermomechanic model (XUV-ABLATOR code) taking into account laser heating and surface evaporation of the lithium fluoridetarget occurring on a nanosecond timescale. This step was followed by the application of two-dimensional hydrodynamic solver for description of laser-produced plasma plume expansion dynamics. The calculated plume lengths determined by numerical simulations were compared with a simple adiabatic expansion (blast-wave) model.

Migration channels produced by laser ablation for substrate endothelialization

Major R., Maksymow K., Marczak J., Lackner J., Kot M., Major B.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2012

Vol. 60, nr 2

337-342

Seeding of cells on functional, biocompatible scaffolds is a crucial step in achievement the desired engineered tissue. In the present study, a pulsed laser modification onto inorganic substrate was made to promote endothelium cells migration and spread. Presented scaffolds were fabricated on carbon and titanium based coatings. Fabricated films provided very good mechanical properties together with a chemical stability preservation. The substrate modification consisted of grid-like template fabrication of micrometer size meshes. The microstructure analysis of laser traces revealed the grain size increase in the zone of laser beam interaction, which exerts an influence on a surface topography. Endothelium cells locomotion was observed within 10 day time period. As a result it was shown that the modified area enhanced cells adhesion with a preferred static behavior. The performed research work improved our understanding on the pulsed laser ablation process and template size influence on cells spatial arrangement. It constituted an important step towards fabrication of inorganic, biocompatible scaffolds for successful substrate endothelialization.

Structure and optical properties of (Alqx)/Al2O3 ethanol colloids

Chen Q. H., Wang W. J., Zhang W. G.

Materials Science Poland

2010

Vol. 28, No. 1

15--23

An investigation into the structure and chemical stability of green light emitting aluminum complexes of 8-hydroxyquinoline (Alqx)/Al2O3 colloids was performed. (Alqx)/Al2O3 ethanol colloid was characterized by the high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy, thermogravimetric and simultaneous differential thermal analysis, and thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TGA/FTIR). The results show that the (Alqx)/Al2O3 nanoparticles are composed of an inner core of crystalline Al2O3 and an outer layer of 8-hydroxyquinoline (Q) coordinated to the surface aluminum ions of Al2O3 the nanoparticles. The luminescence intensity of the (Alqx)/Al2O3 ethanol colloids decreased upon the increasing aging time, and is accompanying by the presence of a brown material and a dark brown deposit produced in the colloids. The main component of the deposit was polystyrene. These findings can be explained by a process where Q coordinates to the surface ions of the Al2O3 particles, followed by degradation of the pyridine ring of 8- hydroquinonline, leading to the formation of polystyrene.