Photoluminescence (PL) and Raman spectroscopies of core/shell quantum dots (QDs) were studied under hydrostatic pressure at room temperature. Two phase transitions, at 69 and , respectively, were observed, which correspond to wurtzite-rocksalt and rocksalt-cinnabar structural transformations. The full width at half maximum of PL peaks was found to decrease anomalously approximately 30% with pressure. These experimental data show significant difference between the core/shell QDs and simple bare CdSe QDs or bulk CdSe, implying the ZnS shell plays a dominant role in structural stability and electronic state of such system.
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