SURFACE CAPPING OF TiO₂ COLLOIDAL NANOPARTICLES STUDIED BY FOURIER TRANSFORM RAMAN SPECTRA

Surface capping of TiO₂ colloid nanoparticles with tetrasulfonated gallium phthalocyanine chloride (GaTsPc) was studied by Fourier Transform (FT) Raman spectra. A striking FT-Raman signal enhancement of GaTsPc is observed, indicating that a surface complex is formed during surface capping of GaTsPc dye molecules on TiO₂ colloid via sulfonate groups. This effect is attributed to a strong Raman resonance with the charge transfer transition in the surface complex. Surface complexation also have considerable influences on the FT-Raman signals for TiO₂ nanoparticles.