The knowledge of the orientation of molecules on a surface is a very important piece of information for understanding surface properties. When the surface of a particle is located deep in the colloidal medium, the determination of the surface molecular orientation is quite challenging. We have exploited the intrinsic sensitivity of second harmonic generation from interfaces between centrosymmetric media to meet this challenge.The model system investigated consists of malachite green molecules adsorbed on the surface of polystyrene particles in water with size in the 50 nm-1 micron range. The development of the nonlinear Mie theory for the description of the scattering of light at the second harmonic frequency has been critical for the interpretation of the experimentally observed scattering angular patterns and has enabled the determination of the molecular orientation on the spherical particles [1].[1] Gonella G., Dai H.-L., Phys. Rev. B (2011) 84, 121402(R)

Determination of the molecular orientation on the surface of colloidal particles in solution: A second harmonic scattering study

244th National Meeting (2012)

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