Confinement-induced uncertainty of the crystal momentum relaxes the momentum conservation rule and enables access to phonons with larger momentum. In most zinc-blende materials, only the LO phonon has a strong enough dispersion that results in a characteristic asymmetric peak broadening and red-shift with confinement. The confinement effect can be thus quantified from the lineshape of the first order Raman peaks and the phonon dispersion through the spatial correlation model. This model assumes that the phonon wavefunction is spatially constrained in a sphere and predicts the following sizedependent Raman lineshape: