[Blue shift of Raman peak of DBS/TiO2 nanoparticles]

Nanosized TiO2 coated with dodecylbenzenesulphonic acid (DBS) was prepared using the hydrothermal procedure. The average size of DBS/TiO2 is very small, about 8 nm. Raman spectra from DBS/TiO2 was measured, and scattering signals from both TiO2 and DBS were observed. It was found that in contrast to the red shift of Raman peaks in the nanoparticle with reducing the particle size, a blue shift, namely the Raman peak shift to higher frequency, in the nanosized DBS/TiO2 particles was recorded. Meanwhile, we found that every Raman peak of TiO2 show different amount of Raman shifts. We discussed the possible origin of the blue shift.