Spectroscopic study of the growth mechanism of silver microclusters

Polymer-protected silver microclusters have been obtained by room-temperature alcoholic reduction of metal ions in presence of a polymeric stabilizer (i.e., poly(N-vinyl-2-pyrrolidone) (PVP)). The method allows one to prepare bulk quantities of the material with a control of size from a molecular level. Spectrophotometric monitoring technique has been employed to investigate the influence of the aging of the protective PVP layer on the microcluster growth rate, under different reaction temperatures and PVP/ethylene glycol weight ratios. The aging time of the polymeric stabilizer solution has been found to play a fundamental role in the reproducibility of the microcluster growth kinetic. In addition, the microcluster growth process has resulted governed by a diffusion-controlled mechanism.