AVS 49th International Symposium
    Surface Engineering Monday Sessions
       Session SE+NS-MoA

Paper SE+NS-MoA7
Formation and Optical Properties of Peridically Arranged Silver Nanoparticles by Irradiation with Linear Polarized Ultrashort Laser Pulses

Monday, November 4, 2002, 4:00 pm, Room C-111B

Session: Nanoparticle and Nanofiber Surface Technologies
Presenter: D. Katzer, Fraunhofer-Institute for Mechanics of Materials Halle, Germany
Authors: A. Heilmann, Fraunhofer-Institute for Mechanics of Materials Halle, Germany
A. Kiesow, Fraunhofer-Institute for Mechanics of Materials Halle, Germany
D. Katzer, Fraunhofer-Institute for Mechanics of Materials Halle, Germany
A. Podlipensky, Martin-Luther-University Halle, Germany
G. Seifert, Martin-Luther-University Halle, Germany
H. Graener, Martin-Luther-University Halle, Germany
Correspondent: Click to Email
We report on a new and simple method to generate periodically ordered metallic, wire-like structures in an organic polymer-like matrix by irradiating thin films with series of ultrashort laser pulses. The films, which were deposited by alternating plasma polymerization and metal evaporation, are characterized by a two-dimensional particle size and shape distribution, i.e. all silver particles are arranged on one plane within the plasma polymer matrix. After laser irradiation with linearly polarized ultrashort (pulse duration < 150 fs), the nanostructure of the film changes from a relatively uniform particle distribution to a formation of an ensemble with metal particle nanowires. This was demonstrated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Material ablation during laser irradiation was not observed. The individual nanowires are between 100 to 250 nm wide with equal line space ratio. The obtainable structure size is not a function of the focusability of the laser and is significantly smaller than the laser wavelength used. The orientation of these wire-like structures is correlated to the linear polarization of the laser pulses, and is independent on the write direction of the laser beam. This dependence on laser polarization results in anisotropic optical properties. The optical extinction spectra were measured by locally resolved optical spectroscopy and by using linearly polarized light. The shift of the extinction peak depending on different steps of nanowire formation was analyzed. The optical spectra were correlated with the different nano-structures and various models were discussed to explain the material transport in the film.