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Title: Determination of plasma frequency, damping constant, and size distribution from the complex dielectric function of noble metal nanoparticles

This paper develops a novel method for simultaneously determining the plasma frequency ω{sub P}   and the damping constant γ{sub free} in the bulk damped oscillator Drude model, based on experimentally measured real and imaginary parts of the metal refractive index in the IR wavelength range, lifting the usual approximation that restricts frequency values to the UV-deep UV region. Our method was applied to gold, silver, and copper, improving the relative uncertainties in the final values for ω{sub p} (0.5%–1.6%) and for γ{sub free} (3%–8%), which are smaller than those reported in the literature. These small uncertainties in ω{sub p} and γ{sub free} determination yield a much better fit of the experimental complex dielectric function. For the case of nanoparticles (Nps), a series expansion of the Drude expression (which includes ω{sub p} and γ{sub free} determined using our method) enables size-dependent dielectric function to be written as the sum of three terms: the experimental bulk dielectric function plus two size corrective terms, one for free electron, and the other for bound-electron contributions. Finally, size distribution of nanometric and subnanometric gold Nps in colloidal suspension was determined through fitting its experimental optical extinction spectrum using Mie theory based on the previously determinedmore » dielectric function. Results are compared with size histogram obtained from Transmission Electron Microscopy (TEM)« less
Authors:
;  [1] ; ;  [1] ;  [2]
  1. Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina)
  2. (Argentina)
Publication Date:
OSTI Identifier:
22402797
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; COPPER; DAMPING; DIELECTRIC MATERIALS; DISTRIBUTION; FUNCTIONS; GOLD; LANGMUIR FREQUENCY; NANOPARTICLES; NANOSTRUCTURES; OSCILLATORS; REFRACTIVE INDEX; SERIES EXPANSION; SILVER; SPECTRA; TRANSMISSION ELECTRON MICROSCOPY; WAVELENGTHS