Multiphonon probe in ZnS quantum dots

Raman spectroscopic studies have been performed for ZnS nanoclusters in this study. Cluster size dependent multiphonon properties are reported in detail. A flurry of zone boundary phonons is demonstrated in the scattering process. A strong deformation potential (DP) dominated Raman spectra are reported for cubic ZnS nanocluster of diameter with ∼2.2 nm in size below the quantum confinement. Transverse optic (TO) mode in the multiphonon process shows only even order overtones for 2.2 nm cluster, suggesting the dominance of a two‐phonon process and its integral multiples. The possibility of surface oxidation in the smallest cluster is ruled out as a plausible explanation for the observed even order TO modes which resemble the higher order modes of ZnO. A wave vector‐independence of electron–phonon interaction in quantum dots leads to strong dependence on DP‐related phenomenon. A large DP value for the second‐order process in ZnS than that with respect to the first‐order process is made responsible for the observed phenomenon. Copyright © 2010 John Wiley & Sons, Ltd.