Spectroscopy on rare gas–doped silver clusters in helium droplets

The optical spectrum of Ag8 in a helium droplet, first measured by Federmann et al. [Eur. Phys. J. D 9, 11 (1999)], is studied over a broad wavelength range (237–450 nm) by resonant two photon ionization. A strong resonance is found in accordance to recent ab initio calculations. Doping the droplet additionally with rare gas atoms leads to a shift of the mean resonance position, which depends on the type and the number of attached atoms. In contrast to the red-shift obtained for argon, krypton, and xenon, for neon a net shift of the resonance to shorter wavelengths is observed. The dosage-dependence of the displacements will qualitatively be explained.