In this work, we report on a detailed quantitative nanomechanical mapping of freestanding films of poly(ethylene terephthalate) (PET) and the composite PET/expanded graphite (EG) with 0.4% in weight of the nanoadditive, and of these materials nanostructured by laser irradiation. By using atomic force microscopy, we obtained

We demonstrate the formation of laser-induced periodic surface structures (LIPSS) in bismuth (Bi) thin films by irradiation with nanosecond laser pulses. We report on the formation and the destruction of the LIPSS as a result of the delivered number of pulses; both the formation and destruction threshold were very well determined. Results show that the obtained LIPSS are perpendicular to the laser polarization, and their ripple periodicity is on the order of the irradiation wavelength. Although all the irradiation experiments were done in ambient air, Raman micro-spectroscopy indicates that the LIPSS are constituted by metallic bismuth, i. e. the LIPSS formation is oxidation free.

No abstract

In this work, we report the fabrication of bismuth thin films on glass substrates by Pulsed Laser Deposition. A focused beam of a Nd:YAG laser (9 ns, 10 Hz, 1064 and 532 nm) was utilized to carry out the ablation of a high purity Bi target. The per pulse laser fluence was varied between 0.95 and 1.35 J/cm2, depending on the laser wavelength used. The deposits were characterized by SEM and XRD to analyze the surface morphology of thin films and their crystalline structure, respectively. The SEM micrographs showed differences in roughness, which increased with the laser wavelength. The diffractograms revealed the formation of Bi thin films with a polycrystalline structure or with a preferential orientation, depending on the mean kinetic energy of the plasma ions. The as deposited bismuth thin films were irradiated with a non-focused laser beam at low energies below the ablation threshold. In the laser treated area, it could be observed the formation of periodic structures, known as LIPSS (laser induced periodic surface structures). Depending on the crystallographic structure of the irradiated film, the formed LIPSS showed different characteristics, such as width and shape.