Self-influence of a femtosecond laser beam upon ablation of Ag in liquids

Formation of nanoparticles of either Au or Ag is reported under ablation of metallic targets exposed to radiation of a femtosecond Ti:sapphire laser (wavelength of 810 nm, pulse width of 120 fs) in either water or ethanol. Nanoparticles are characterized by UV-visible spectroscopy and transmission electron microscopy. Nanoparticles of Ag are several times smaller than those of Au at otherwise equal conditions. The effect is attributed to the self-influence of a laser beam via generation of the second harmonics of the laser radiation on Ag clusters and its good matching to the plasmon resonance of Ag. PACS 42.62.-b; 61.46.+w; 78.66.-w