Surface‐enhanced Raman scattering investigations on silver nanoparticles deposited on alumina and titania nanotubes: influence of the substrate material on surface‐enhanced Raman scattering activity of Ag nanoparticles

Abstract

Silver nanoparticles deposited on various ‘inert’ porous materials (mainly Al 2 O 3 and TiO 2 ) are often used as substrates for surface‐enhanced Raman scattering (SERS) measurements. In this study, we used the sputter deposition technique to cover tubular arrays of Al 2 O 3 and TiO 2 with Ag nanoparticles. Raman spectra of pyridine (as a probe molecule) and of two selected dyes (5‐(4‐dimethylaminobenzylidene)rhodanine and 5‐(4‐(dimethylamino)benzylidene)‐3‐(3‐methoxypropyl)rhodanine) adsorbed on fabricated Ag/TiO 2 ‐n/Ti and Ag/Al 2 O 3 ‐n/Al substrates were measured. We found that the SERS spectra of pyridine adsorbed on Ag nanoparticles deposited on an Al 2 O 3 ‐n/Al substrate are distinctly different from those measured for an Ag/TiO 2 ‐n/Ti composite. Similar effects were observed for dyes adsorbed on the surface of both composites. The spectral differences between two kinds of composites (Ag/TiO 2 ‐n/Ti and Ag/Al 2 O 3 ‐n/Al) are discussed in terms of (1) the modified electronic structure of the Ag nanoparticles due to their interaction with different substrate materials and (2) the different atomic topology of the metal particles thus deposited on the surfaces of the substrates. Composite samples were also studied with the aid of scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) to reveal their characteristic morphological and chemical features. Copyright © 2012 John Wiley & Sons, Ltd.