Upper limit of blue shift in the photoluminescence of CdSe and CdS nanosolids Original Research Article

Adding the effect of surface bond contraction to the Hamiltonian of an extended solid leads to a new mechanism indicating that the blue-shift in the photoluminescence (PL) of CdS and CdSe nanosolids arises from the surface-relaxation-enhanced binding energy and the PL shift depends on the portion of surface atoms of the solid. Consistency between predictions and observations evidences that a surface bond contracts more than it does on a flat surface when the surface curvature increases and that the Cd–Se bond contracts faster than the Cd–S bond when the solid approaches to the lower end of size limit.