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  Hinrichs, K.; Rappich, J.; Tsankov, D.: Surface-Enhanced Infrared Ellipsometry of Nanostructured Layers. Asian Chemistry Letters 13 (2009), p. 29-34

Abstract:
IR absorption bands of organic films in contact with metal nanoparticles on dielectric substrates display increased intensities and this effect is known as surface enhanced infrared absorption (SEIRA). Stronger band enhancement is achieved in thicker films at percolation threshold when the metal islands start to coalesce. The absorption bands, however, become asymmetric and take on a dispersive shape. The percolation threshold of gold island films on passivated Si-H surfaces is reached at thicknesses between 3-5 nm. Thinner discontinuous metal films produce no distinct SEIRA effect. The effect is, however, much higher when the metal nanoparticles are vapor deposited on a previously modified dielectric surface. In this paper we show that thin multilayered nitrobenzene film electrochemically grafted on Si-H surface causes differently developed island structure to a thin gold film deposited on it. The IR ellipsometric bands of a monolayer of hexadecanethiol self assembled on top of the gold nanoparticles showed a stronger SEIRA effect.