Blueshifts in the ultraviolet absorption spectra of cerium oxide nanocrystallites

Blueshifts in the ultraviolet absorption spectra have been observed in cerium oxide nanocrystallites. The mechanism of the absorption is a charge-transfer optical transition. The relationships among the blueshift, valence state of cerium ions, and the particle size are formulated. The blueshifts are well explained for diameters down to less than a few nanometers by the change in the electronic band structure. (C) 2003 American Institute of Physics.