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Rauch, S. ; Eichhorn, K.-J. ; Stamm, M. ; Uhlmann, P.
Spectroscopic ellipsometry of superparamagnetic nanoparticles in thin films of poly(N-isopropylacrylamide)

The versatility of spectroscopic Vis-ellipsometry (SE) to determine thin film properties was used to study Fe3O4-nanoparticles (NPs) embedded in thin films of poly(N-isopropylacrylamide). By using the optical constants of bulk Fe3O4 (magnetite) the volume fractions in different NP-polymer composites (0–3 vol. %) could be quantified with SE and verified with scanning electron microscopy (SEM) and atomic force microscopy. It was found that the best-fit results from SE matched well with data from SEM until 1 vol. %. The effect of the NP on the evolution of film thickness and surface morphology was analyzed. Over the whole concentration range the data obtained from SE measurements matched well with the suspended values and showed an expected linear behavior. Additionally, the optical constants (n and k) of the nanocomposites were extracted and compared to the pure polymer film. In the measured spectral range the data showed a physical meaningful behavior and the influence of the NP on the optical properties of the thin films could be observed.

Journal of Vacuum Science and Technology : A. Vacuum, Surfaces, & Films 30, 041514 (8pp)


June 2012
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