Raman scattering from microcrystals of MgO

Raman scattering has been observed from microcrystals of MgO which were produced from Mg${(\mathrm{OH})}_{2}$, MgC${\mathrm{O}}_{3}$, and MgO smoke. Particles which had an average diameter of 300 \AA{} gave Raman bands with frequency shifts of 595, 719, and 1096 ${\mathrm{cm}}^{\ensuremath{-}1}$, whereas particles of mean diameter 600 \AA{} gave bands at 592 and 1088 ${\mathrm{cm}}^{\ensuremath{-}1}$. These results are discussed in terms of the macroscopic and microscopic theories that have been used to describe the lattice dynamics of small crystals. Experimental evidence of the inverted Lyddane-Sachs-Teller relation is given.