Both positively and negatively charged colloidal silver particles were prepared from chemical deoxidized methods. Then UV-visible absorption, fluorescence, and surface-enhanced Raman scattering of methyl orange adsorbed onto surfaces of these two kinds of particles were observed and compared with each other. The results indicate that dye molecules may adsorb onto these two kinds of silver surface in differing adsorption orientations with different interactions, which caused the different phenomena. (c) 2006 Elsevier Inc. All rights reserved.