Abstract

The phonon bands appearing in the first order Raman spectrum of a macroscopic crystal have a Lorentzian lineshape peaked at the ω(q = 0) phonon frequencies. If the crystal size is smaller than about 30 nm, the localization of phonon wave function causes the relaxation of the q=0 selection rule which, in turn, results in i) the redshift of the peak position and ii) the low-frequency asymmetric broadening of the Raman bands for materials with a negative phonon dispersion.^[1]

© 1992 IQEC