Adsorbed Dyes onto Nanoparticles: Large Wavelength Dependence in Second Harmonic Scattering

Abstract

Spectrally and polarization resolved second harmonic scattering (SHS) has been used to probe the adsorption of an hemicyanine dye onto polystyrene nanoparticles. The polarization resolved SHS measurements in both the vertically and horizontally output polarization configuration demonstrate the ability of this technique to monitor simultaneously the amount of free dye in solution and the amount of dye species adsorbed onto nanoparticles. Indeed, those two contributions can be discriminated when changing the laser incident polarization angle. Moreover, a large modification appears for the horizontally polarization resolved pattern when the laser excitation wavelength is tuned from 790 to 810 nm. This result is discussed within the framework of nonlinear Mie theory.