Laser ablation: Preparation of ''chemically pure'' Ag colloids for surface-enhanced Raman scattering spectroscopy

''Chemically pure'' Ag colloids as active surfaces for surface-enhanced Raman scattering (SERS) spectroscopy were prepared by laser ablation of an Ag foil in pure water, in the presence of Cl- anions, and in the presence of an adsorbate. SERS-activity of the ablated colloids was proved using 2,2'-bipyridine [bpy] and phtalazine [pht] as adsorbates. Moreover, a SERS-active Ag colloid/adsorbate system was prepared by laser ablation of Ag foil immersed in an aqueous solution of pht. SERS spectra of pht obtained from this system are identical with those of pht added to Ag colloid ablated in pure water. The possibility of preparing a SERS-active system by laser ablation of Ag in the presence of an adsorbate was thus demonstrated, Furthermore, Ag colloid-bpy films were prepared from the laser ablated colloids and their SERS activity proved by obtaining a good quality SERS spectra of bpy. (C) 1997 Elsevier Science B.V.