Photoluminescence of the PbS quantum dots fabricated by the Langmuir-Blodgett technique
The optical and structure properties of the PbS nanoclusters in the Langmuir-Blodgett matrix as well as their properties after the matrix removal in the ammonium atmospheres have been studied. According to the electron microscopy data, it has been established that there are PbS nanoclusters formed on the surface of the samples. It has been found that the matrix removal results in a significant enlargement of the PbS nanocrystals accompanied by the shift of the luminescence into the infra-red range. It has been shown that the PL intensity of PbS quantum dots (QDs) in the matrix decreases with the temperature decrease due to the carrier transfer into defect QDs whereas the the luminescence intensity of the PbS nanocrystals without a matrix grows at the temperature increase.
Abstract A simple pseudopotential (PP) model developed by us earlier was used here to study lattice dynamics and lattice statics of copper. Comparison of the accuracy attainable in different model calculations of the off-symmetry phonon frequencies was made, and the PP model appeared to be at least as accurate as the embedded atom method (EAM). We suggest that calculation of further lattice properties is necessary to evaluate any microscopic model properly. As an example we give a brief review of the PP model application in the lattice dynamics of alloys including the calculation of frequency shifts in different palladium-based alloys.