Time Resolved Chemisorption of I- and SH- on Colloidal Silver Particles (A Stopped-Flow Study)

Article abstract of DOI:10.1021/j100031a008

An aqueous silver sol (mean particle size: 6 nm) is mixed with KI and NaSH solution, and the changes in optical absorption and light scattering are recorded.When iodide adsorbs on the silver particles, the 225-nm band of I^- disappears concurrently with the decreasing of the silver plasmon absorption band.In the same time range, the intensity of light scattering slightly decreases, which is explained as a detachment of the colloidal particles from the polyphosphate stabilizer.At a later stage, the silver plasmon band is red-shifted and the light scattering finally increases again, which is understood in terms of loose cluster formation of the particles.The adsorption of H2S leads to damping and a simultaneous blue shift of the plasmon absorption band.The adsorption of H2S is faster than that of SH^-, as there is no Coulomb repulsion between the adsorbant and the negatively charged metal particles.