Laser-induced fragmentation and melting of cadmium and copper nanoparticles

Irradiation of cadmium particles in aqueous solution by a pulsed Nd:YAG las er at 355 nm was found to cause size reduction of the particles. The temper ature of the cadmium particles was calculated from the laser energy absorbe d by the particles, and was found to increase as high as the boiling point of cadmium. The shape change and size reduction are considered to occur thr ough melting and vaporization of the cadmium particles. The results are exp lained on the basis of the rate of energy deposition compared with electron -phonon and phonon-phonon relaxation processes. The electron dynamics was s tudied in copper metal nanoparticles using transient absorption spectroscop y after excitation with 532 nm ps laser pulses. (C) 2001 Elsevier Science L td. All rights reserved.