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Gold nanoparticle assemblies with different particle densities were immobilized upon functionalized glass substrates and their morphology and optical properties are analysed with TEM and UV–vis absorption spectroscopy. The efficiency of self-assembled gold colloidal nanoparticles as SERS-active substrates at 633 nm excitation line is evaluated by employing p-aminothiophenol. The average enhancements in the range of 105–107 are consistent with signals being dominated by molecules adsorbed at junctions inside nanoparticle assemblies. We employ an annealing treatment to induce changes in the initial morphology of gold assemblies and produce sensitive LSPR substrate. The sensitivity of the as-prepared substrate to transduce changes of the surrounding medium refractive index is further assessed.

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Metallic multilayer structures consisting of self-assembled nanoparticles are prepared by successive immersion of a functionalized glass substrate in a gold colloidal suspension, and are characterized by UV/Vis spectroscopy and atomic force microscopy. The ability of the thin film to concomitantly enhance the Raman and IR signals of an adsorbed molecule is evaluated and a detailed analysis of the recorded spectra is provided, which emphasizes the capability of these complementary methods to provide information about the adsorbed species. This unique surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption (SEIRA) substrate could be further used for applications in the elucidation of the structure of a great variety of adsorbed samples.