Analysis of the main optical mechanisms responsible for fragmentation of gold nanoparticles by femtosecond laser radiation.

F. A. VIDELA; G. A. TORCHIA; D. C. SCHINCA; L. B. SCAFFARDI; P. MORENO; C. MÉNDEZ; GIOVANETTI, L.J.; J. M. RAMALLO-LOPEZ; L. ROSO

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Año: 2010 vol. 107 p. 1143081 - 1143088

0021-8979

Studies of fragmentation process of gold nanoparticles (Nps) in deionized water after generation by femtosecond laser ablation were performed. To analyze the fragmentation process, direct IR ultrafast pulses or super-continuum (SC) radiation focused in the colloidal solution were used in separate steps. IR pulses and SC generated externally in a sapphire crystal or directly inside the water were applied under low fluence regime. In the latter cases, to evaluate the effect on fragmentation of the different spectral bands present in the SC, we have determined different efficiency regions characterized by means of the product between the spectral response and the optical extinction spectrum corresponding to the initial Nps solution. From the analysis of this product function, we can conclude that the main fragmentation mechanism is due to linear absorption in the visible region. Likewise, the SC generated in water resulted more efficient than the SC obtained externally by a sapphire crystal. This fact may be attributed to the blue broadening of the water SC spectrum as compared with the sapphire SC due to the large intensity used for its generation. Transmission Electron microscopy and small angle x-ray scattering measurements support the results found from optical extinction spectroscopy.