SERS SPECTROSCOPY WITH AG COLLOIDS

The possibilities of overcoming some drawbacks encountered in SERS spe ctroscopy with Ag colloids are presented and discussed. Modification o f Ag colloidal surface by molecular spacer is shown to be a suitable w ay for obtaining SERRS spectra of unperturbed free-base porphyrin spec ies as well as of a metalloporphyrin which cannot be spontaneously ads orbed on a bare Ag colloidal surface. Furthermore, preparation of stab le, long-term SERS-active two-dimensional Ag colloid-adsorbate films i s described and the effect of the adsorbate structure on the morpholog y of the films, expressed in terms of fractal dimension, is discussed. (C) 1997 Elsevier Science B.V.