Quantum size effect in TiO nanoparticles: does it exist?

We have examined the quantum size effect in anatase TiO2 nanoparticles. No shift of the band gap energy has been observed for sizes 2 RG1.5 nm. On the other hand, we have found unusual variation of the oscillator strength of the first allowed direct transition. The results indicate considerable structural size effect, which disables the effective mass approximation EMA.in these nanocrystallites. q2000 Elsevier Science B.V. All rights reserved.