Figure 9.

On (a), an optical image of $2400$nm thick ${\mathrm{CeO}}_2$ surface is displayed, and on (b), an intensity distribution map for the main Raman peak, whose Stokes shift is of 1338 cm${}^{-1}$ from the laser frequency $12.738\times {10}^3$ cm${}^{-1}$, i.e., wavelength $\lambda =785$ nm (CCD: red = 1700 counts, violet = 300 counts).