title: Assessment of femtosecond laser induced periodic surface structures on polymer films.
abstract: In this work we present the formation of laser induced periodic surface structures (LIPSS) on spin-coated thin films of several model aromatic polymers including poly(ethylene terephthalate), poly(trimethylene terephthalate) and poly carbonate bis-phenol A upon irradiation with femtosecond pulses of 795 and 265 nm at fluences well below the ablation threshold. LIPSS are formed with period lengths similar to the laser wavelength and parallel to the direction of the laser polarization vector. Formation of LIPSS upon IR irradiation at 795 nm, a wavelength at which the polymers absorb weakly, contrasts with the absence of LIPSS in this spectral range upon irradiation with nanosecond pulses. Real and reciprocal space characterization of LIPSS obtained by Atomic Force Microscopy (AFM) and Grazing Incidence Small Angle X-ray Scattering (GISAXS), respectively, yields well correlated morphological information. Comparison of experimental and simulated GISAXS patterns suggests that LIPSS can be suitably described considering a quasi-one-dimensional paracrystalline lattice and that irradiation parameters have an influence on the order of such a lattice. Fluorescence measurements, after laser irradiation, provide indirect information about dynamics and structure of the polymer at the molecular level. Our results indicate that the LIPSS are formed by interference of the incident and surface scattered waves. As a result of this process, heating of the polymer surface above its glass transition temperature takes place enabling LIPSS formation.
authors.affiliation: Instituto de Química Física Rocasolano, IQFR-CSIC, Serrano 119, 28006 Madrid, Spain. e.rebollar@iqfr.csic.es
authors.forename: Esther
authors.initials: E
authors.lastname: Rebollar
authors.forename: Javier R
authors.initials: JR
authors.lastname: Vázquez de Aldana
authors.forename: Ignacio
authors.initials: I
authors.lastname: Martín-Fabiani
authors.forename: Margarita
authors.initials: M
authors.lastname: Hernández
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Rueda
authors.forename: Tiberio A
authors.initials: TA
authors.lastname: Ezquerra
authors.forename: Concepción
authors.initials: C
authors.lastname: Domingo
authors.forename: Pablo
authors.initials: P
authors.lastname: Moreno
authors.forename: Marta
authors.initials: M
authors.lastname: Castillejo
mesh_terms: D007834:Lasers; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry*; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D059808:Polyphenols / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors
chemical_list: D011093:Polyethylene Terephthalates; D059808:Polyphenols; C498323:poly(trimethylene terephthalate); D011092:Polyethylene Glycols