Aggregation of Silver Particles in Silver Alginate Films

The variation of the absorption spectra of silver alginate (SA) films upon irradiation with 253.7 nm light has been studied. When the SA film was photolyzed at room temperature ( T = 300 K) in vacuum, the intense colloidal absorption band around λ = 407 nm due to large silver particles (metallic silver particles) appeared. Irradiation at liquid nitrogen temperature ( T = 77 K) caused the growth of a small peak around 337 nm, together with a broad background absorption extending from 600 nm to less than 200 nm. Major products at low temperature seem to be small silver particles (relatively large silver clusters and quasi‐metallic silver particles). After photolysis at 77 K and heating until 300 K was achieved, the variation of the absorption spectrum of the SA film during dark storage in vacuum was monitored. The 337 nm peak was slightly decreased in the initial stage and then, the colloidal absorption band (415 nm) increased monotonously for 20 h. Rapid diffusion of silver atoms and clusters under irradiation in air at room temperature has been suggested.