INVESTIGADORES
SCAFFARDI Lucia Beatriz
congresos y reuniones científicas
Título:
Dielectric function and optical extinction spectroscopy for sizing Ag nanoparticles generated by fs laser ablation
Autor/es:
JESICA M. J. SANTILLÁN; LUCÍA B. SCAFFARDI; FABIÁN A. VIDELA; DANIEL C. SCHINCA
Lugar:
Porto, Portugal
Reunión:
Conferencia; RIAO/OPTILAS 2013 VIII Iberoamerican Conference on Optics XI Latinamerican meeting on Optics, Lasers and Applications; 2013
Institución organizadora:
FCUP, Porto, Portugal
Resumen:
The study of optical properties of silver nanoparticles (Nps) is of great interest in the last years for your applications in several fields of science and technologies. This work analyzes the separated contribution of free and bound electrons on the dielectric function of silver Nps. The contribution of free electrons is corrected for particle size through the modification of the damping constant to account the extra collisions with the boundary for sizes smaller than 10 nm. For bound electron contribution, we considered the interband transitions from the d-band to the conduction band including the dependence of the electronic density states with size for radii below 2 nm. Taking into account these specific modifications, it was possible to fit the bulk complex dielectric function, and consequently, determine optical parameters and band energy values such as the coefficient for bound electron contribution , gap energy Eg = 1.91 eV, Fermi energy EF = 4.12 eV, and damping constant for bound electrons Hz. These studies are applied to fit experimental extinction spectra of very small spherical core-shell Ag-Ag2O Nps generated by ultrafast laser ablation of a solid target in water. From the fitting, it was possible determining the distribution of core radius and shell thickness of the Nps. The results from AFM and TEM analysis performed on the obtained samples agree with the sizing obtained by Optical Extinction Spectroscopy, showing that the latter is a good complementary technique to standard microscopy methods.