Photothermal Efficiency of Gold Nanoparticles Using CW Z-Scan Technique in the Visible Range

The photothermal effect may be used in a variety of applications such as cancer treatment, biological microscopy… Light scattering from plasmonic nanoparticles (NPs) can be sufficiently strong to enable single-particle observations in dark-field microscopy. The relative contributions of light scattering and light absorption are of paramount importance in the characterization of NPs and their selection and optimization for a specific application. CW single beam Z-scan technique is applied to determine the absorption and scattering efficiencies on different size of spherical gold nanoparticles (5, 40, 60, 80 nm). Experimental tests are carried out at three different wavelengths at blue, green and red wavelengths. The quantum yields are determined through Thermal Lens (TL) effect. Details of the measurement method characteristics are given for relatively high absorption procedure using Gaussian top-hat beams. The validity of our approach is confirmed by comparing the obtained scattering data with that of the theoretical values given by the Mie theory. Very good agreement is found within the experimental errors.