Laser-based method for fabricating monodisperse metallic nanoparticles

An experimental method is presented for fabrication of almost monodisperse metal nanoparticles on substrate surfaces. It relies on substantial narrowing of broad size distributions through irradiation with short laser pulses by exploiting the size dependent optical absorption coefficient of the metal particles. Successive irradiation by applying two laser wavelengths completely removes the smallest clusters of the distribution and causes a size reduction of the largest particles. Finally, only clusters with diameters in a very narrow size interval remain on the surface. By using this method, Ag clusters with mean diameters of [d] = 10 nm and size distributions with standard deviations of Delta d/[d] = 0.13 have been prepared. (C) 1999 American Institute of Physics. [S0003-6951(99)01018-9].