Strain-induced confinement of excitons in quasi-free AgI nanoparticles

The optical spectra of vapor quenched metastable Ag-Cu thin films progressively iodized under ambient conditions have been measured. Delayed evolution and inhomogeneous broadening of the exciton absorption at 420 nm of the spatially confined gamma-Agl nanoparticles were clearly seen by the development of Z(1,2) exciton peak - iodization being controlled by the as-quenched Ag-Cu clusters. Cu addition not only restricts the particle size, but also favors the island type growth mode.