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CPP: Chemische Physik und Polymerphysik

CPP 2: Polymer Surfaces II

CPP 2.5: Vortrag

Montag, 8. März 2004, 12:00–12:15, H 37

Near-field infrared microscopy & nanospectroscopy of polymers — •Thomas Taubner and Fritz Keilmann — Max-Planck-Institut für Biochemie, Am Klopferspitz 18a, 82152 Martinsried

Nanoscale composites such as self-organizing block copolymers are an elegant way of structuring templates for widely different applications. Material discrimination of nanoscale compostites can be a difficult task, because conventional optical and infrared microscopes are limited in resolution and other methods such as electron microscopy or AFM either lack contrast or are ambiguous. A new approach of near-field microscopy is capable of high spatial resolution and chemical sensitivity[1] given by an infrared spectrum.

We improved this scattering-type near-field infrared microscope (s-SNIM) to determine for the first time the near-field infrared spectrum of a 60-nm thin polymer film by tuning a CO-laser through a strong absorption band of PMMA around 5.8 µm wavelength. The obtained near-field spectrum is characteristically different from the usual lorentzian shape of far-field absorption, but rather similar to a reflectivity spectrum. By imaging at chosen wavelengths to maximize contrast we identify PMMA in a 70 nm thin film of a nanoscale polymer blend. The smallest aggregates of 70 nm diameter are easily resolved, promising a resolution of less than 20 nm [2].

References: [1] B. Knoll and F. Keilmann, Nature 399, 134 (1999) [2] T. Taubner, R. Hillenbrand and F. Keilmann, Journal of Microscopy 210, 311 (2003)