Studies on the electronic and vibrational states of colloidal CdSe/ZnS quantum dots under high pressures

The electronic and vibrational states of colloidal core/shell CdSe/ZnS quantum dots are studied at room temperature by using high pressure optical measurements. Pressure-induced quadratic variations of lattice constants can be observed clearly from both photoluminescence ( PL) and Raman spectra up to similar to 7 GPa. This quadratic relationship is consistent with the theoretical prediction. The pressure coefficients of linear and quadratic terms are 32 meV GPa(-1), -1 meV GPa(-2) for PL and 4.2 cm(-1) GPa(-1), -0.1 cm(-1) GPa(-2) for Raman measurements, respectively.