Patent ID: 8246714

Claim:
A method of producing nanoparticle colloids, comprising: generating ultrashort pulsed laser beams at a pulse repetition rate greater than 100 kHz, each pulsed laser beam having a pulse with pulse energy less than about 10 μJoules, and a pulse duration up to about 10 picoseconds (ps); irradiating a target with said pulsed laser beams, said target being disposed in liquid that is substantially transparent at a wavelength of said pulsed laser beams, said target being a source material for production of metal or metal-alloy nanoparticles that result from target material modification, wherein said liquid is substantially free of any stabilizing chemical agents; and imparting relative motion between said pulsed laser beams and said target with at least movement of the pulsed laser beams to limit heat accumulation and to substantially avoid blocking of laser pulses by scattering and absorption from nanoparticle colloids that are formed in said liquid at said repetition rate, wherein at said repetition rate above 100 KHz a size distribution dominated by nanoparticles results from fragmentation of particles in the laser plume, and highly stable nanoparticle colloids are produced with said steps of generating, irradiating, and imparting, notwithstanding said liquid being substantially free of any stabilizing chemical agents.