Surface chemistry of colloidal silver: surface plasmon damping by chemisorbed iodide, hydrosulfide (SH-), and phenylthiolate

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 I 2 (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