Figure 11
(a) A distorted monoclinic Ag2S (100) plane connects with the wurtzite CdS (001) plane, which served as the initial DFT model. (b) Elastic energy of the rod as a function of the segment separation (center-to-center). (c) Z-axis strain for the case of two mismatched segments at a center-to-center separation distance of 14.1 nm (top) and 12.1 nm (bottom). The elastic interaction between the segments is greatly reduced for the separations >12.1 nm. Arrows show the placement of the mismatched segments. The CdS rods used for the valence force field calculations (b and c) were 4.8 nm in diameter, with two 4.8–by–4.0-nm lattice-mismatched segments. Effective elastic constants for the mismatched segments were from the ab initio calculations for the monoclinic Ag2S.59 (d) Visible and (e) NIR PL spectra at l=400- and 550-nm excitation, respectively. Coupling between the CdS and Ag2S is evident by the complete quenching of the visible PL (d) in the heterostructures. The shift in NIR PL (e) is due to quantum confinement of the Ag2S. Copyright 2007, AAAS.
