Adsorption and orientation of thiacarbocyanine J- and H-aggregates adsorbed on single Ag nanoaggregates were modeled by their time dependence of surface-enhanced Raman scattering ( SERS) spectra. The time dependence was well approximated with single exponential curves, the decay times ( half lifetimes) of which varied every Ag nanoaggregates. The observed decay times were approximately classified into long, medium, and short ones. The classification was ascribed to three-type adsorption of J- or H-aggregates of thiacarbocyanine, namely the horizontally-oriented J- aggregate, the horizontally-oriented H-aggregate, or the vertically-oriented H-aggregate on the surface of a single Ag nanoaggregate. (C) 2010 Elsevier B. V. All rights reserved.