title: In situ monitoring of laser-induced periodic surface structures formation on polymer films by grazing incidence small-angle X-ray scattering.
abstract: The formation of laser-induced periodic surface structures (LIPSS) on model spin-coated polymer films has been followed in situ by grazing incidence small-angle X-ray scattering (GISAXS) using synchrotron radiation. The samples were irradiated at different repetition rates ranging from 1 up to 10 Hz by using the fourth harmonic of a Nd:YAG laser (266 nm) with pulses of 8 ns. Simultaneously, GISAXS patterns were acquired during laser irradiation. The variation of both the GISAXS signal with the number of pulses and the LIPSS period with laser irradiation time is revealing key kinetic aspects of the nanostructure formation process. By considering LIPSS as one-dimensional paracrystalline lattice and using a correlation found between the paracrystalline disorder parameter, g, and the number of reflections observed in the GISAXS patterns, the variation of the structural order of LIPSS can be assessed. The role of the laser repetition rate in the nanostructure formation has been clarified. For high pulse repetition rates (i.e., 10 Hz), LIPSS evolve in time to reach the expected period matching the wavelength of the irradiating laser. For lower pulse repetition rates LIPSS formation is less effective, and the period of the ripples never reaches the wavelength value. Results support and provide information on the existence of a feedback mechanism for LIPSS formation in polymer films.
authors.affiliation: †Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Rebollar
authors.affiliation: ‡Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Rueda
authors.affiliation: ‡Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Martín-Fabiani
authors.affiliation: ‡Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain.
authors.forename: Álvaro
authors.initials: Á
authors.lastname: Rodríguez-Rodríguez
authors.affiliation: ‡Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain.
authors.forename: Mari-Cruz
authors.initials: MC
authors.lastname: García-Gutiérrez
authors.affiliation: §DUBBLE@ESRF, Netherlands Organisation for Scientific Research (N.W.O.), CS40220, 38043, Grenoble, Cedex 9, France.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Portale
authors.affiliation: †Instituto de Química Física Rocasolano (IQFR-CSIC), Serrano 119, 28006 Madrid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Castillejo
authors.affiliation: ‡Instituto de Estructura de la Materia (IEM-CSIC), Serrano 121, 28006 Madrid, Spain.
authors.forename: Tiberio A
authors.initials: TA
authors.lastname: Ezquerra