Surface optical phonons as a probe of organic ligands on ZnO nanoparticles: An investigation using a dielectric continuum model and Raman spectrometry

Surface optical modes in cylindrical ZnO nanoparticles have been studied theoretically using a dielectric continuum model and experimentally by Raman spectrometry. Theoretically, both wave vector dispersion and outer medium dielectric constant effects have been investigated. Consequently, we attribute the intense peak at $490{\mathrm{cm}}^{-1}$ in the Raman experiment to a surface optical mode related to the top basis of the nanoparticles. We deduce that the bonding of long alkyl chain amines is likely related to the lateral surface of the nanoparticles.