Surface chemistry of colloidal silver: Surface plasmon damping by chemisorbed I-, SH-, and C6H5S-

Abstract

The optical changes that occur upon the addition of iodide, iodine, and colloidal silver iodide to a colloidal solution of silver particles (6-nm mean diameter) were monitored spectrophotometrically. For small concentrations of added I- and I2 (formation of less than a monolayer of adsorbate), the changes in the shape of the silver plasmon absorption band are practically identical. Silver iodide particles in contact with silver particles affect the plasmon band only slightly. It is concluded that the AgI molecules formed by the surface oxidation of the Ag particles by iodine do not possess the properties of bulk AgI. The structure Agδ+I- is proposed as in the case of adsorbed iodide. With in..