Investigation of the SERS Spectra of Hydroquinone Molecule Adsorbed on Titanium Dioxide

The paper analyzes the SERS spectrum of hydroquinone adsorbed on nanoparticles of titanium dioxide (TiO₂). It is seen that the enhancement is stronger for a larger mean size of nanoparticles that is in agreement with an electrostatic approximation. In addition, it is found that there are the lines, which are forbidden in usual Raman spectra. There is also an enhancement caused both by the normal and tangential components of the electric field. This result is in agreement with the theory of SERS on semiconductor and dielectric substrates. The discovery of the forbidden lines indicates on the sufficiently large role of the strong quadrupole light-molecule interaction in such a system.