Surface plasmon resonance analysis of Ag nanoparticles generated by pulsed laser ablation

Antonino Picciotto*, Georg Pucker, Alberto Lui, Lorenzo Torrisi, Daniele Margarone, Pierluigi Bellutti

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Usually the synthesis of such structures is performed using ion implantation techniques or chemical reaction methods or ablating metal targets inside liquid solutions, while here we propose pulsed laser ablation in vacuum for the generation of these particles without any catalytic environment and annealing procedures for their activation. Silver targets were ablated in a vacuum chamber at (10-7 Torr) by Nd:YAG high power pulsed laser at room temperature. The consequent deposition on Si-substrates covered by a ~50 nm thick SiO2 results in the formation of well separated nanometric spheroidal particles of Ag with a diameter of 5-10 nanometers depending on the deposition time. The generation of silver nanoparticles was confirmed by scanning electron microscopy analysis (SEM). The kinetic energy (2 keV) of Ag ions of the non-equilibrium plasma produced by the high power pulse was measured by the aid of Faraday's cup inserted in the interacting chamber. Monte Carlo simulations of ions tracks in solid targets (TRIM) reveal that silver ions are implanted in a region thinner than 10 nm just under the surface. Optical properties of the samples were studied by variable angle ellipsometric spectroscopy (VASE). The ellipsometric spectra were modeled with a 2-layer model. Layer-1 is modeled using the dielectric function of SiO2 and a variable thickness, while Layer-2 is best modeled with a single Lorenztian-oscillator and a constant layer thickness of 7 nm. The imaginary part of the refractive index for layer-2 reveals an absorption band in the energy range characteristic for surface plasmon resonances (SPR) of Ag nanoparticles. The maximum of SPR shifts 372 nm to 414 nm for longer deposition time indicating an increase of the average particle size [1]. Interestingly, although silver nanoparticles are located within the SiO2 layer, nanparticle formation occurs during PLD and needs no additional forming or annealing step.

Original languageEnglish
Title of host publicationPhotonic Materials, Devices, and Applications III
DOIs
Publication statusPublished - 2009
Externally publishedYes
EventPhotonic Materials, Devices, and Applications III - Dresden, Germany
Duration: 04 May 200906 May 2009

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume7366
ISSN (Print)0277-786X

Conference

ConferencePhotonic Materials, Devices, and Applications III
CountryGermany
CityDresden
Period04/05/200906/05/2009

Bibliographical note

Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.

Keywords

  • Laser ablation
  • Silver nanoparticles
  • Surface plasmon resonance

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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