Optical absorption of small silver clusters: Ag(n), (n=4-22).

We present a joint theoretical and experimental investigation of the absorption spectra of silver clusters Ag(n) (4<or=n<or=22). The experimental spectra of clusters isolated in an Ar matrix are compared with the calculated ones in the framework of the time-dependent density functional theory. The analysis of the molecular transitions indicates that the s-electrons are responsible for the optical response of small clusters (n<or=8) while the d-electrons play a crucial role in the optical excitations for larger n values.