Raman scattering by electron-hole excitations in silver nanocrystals

Raman scattering experiments from silver nanocrystals embedded in films of amorphous silica are reported. In addition to the low-frequency peak due to vibrational quadrupolar modes, a broadband is observed in the high-frequency range, with a maximum at about 1000 $cm^{-1}$. The linear dependence of the position of this maximum on the inverse cluster radius is in agreement with the Raman scattering by single or collective electron-hole excitations.