Iodization of rf sputter induced disordered Ag thin films reveals volume plasmon-exciton "transition"We have investigated crystal characteristics and optical properties of CuCl nanocrystals embedded in a SiO 2 glass matrix, which is fabricated by a novel rf-magnetron sputtering technique combined with an inductively coupled plasma ͑ICP͒. The diffraction spots caused by the ͑111͒, ͑220͒, and ͑311͒ planes of the zinc-blende structure of CuCl crystals evidently appear on the electron diffraction patterns under inductively coupled plasma-assisted magnetron-sputtering deposition. Nanoscale particles with the mean particle radius of 4.0 nm are observed in the transmission-electron-microscope images. These results indicate that CuCl nanoparticles are crystallized with a very high quality. This yields optical properties in samples such as the sharp exciton-absorption bands named Z 3 and Z 1,2 . These bands appear with a blueshift, as compared to the bulk-exciton energies caused by the quantum-size effect for the exciton. Only the free-exciton luminescence-band appears without other luminescence bands caused by an impurity.