Absorption Properties of Metal–Semiconductor Hybrid Nanoparticles
The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as input…
Structure determination and homogeneous optical properties of CdS/HgS quantum dots
The structural and optical properties of heterogeneous semiconductor nanoparticles consisting of CdS and HgS are investigated by High Resolution Electron Microscopy (HRTEM) and selective spectroscopy like Hole Burning (HB) and Fluorescence Line Narrowing (FLN). The HRTEM study shows that epitaxy is possible in nanocrystals, provided the crystallites have well defined faceted shapes to begin with. From the HB- and FLN experiments homogeneous absorption and fluorescence spectra are calculated. It could be shown that the absorption is coupled to HgS-like phonons (250 cm -1 ) whereas the emission frequency is closer to the LO phonon frequency of CdS.
Co-Assembly of A–B Diblock Copolymers with B′-type Nanoparticles in Thin Films: Effect of Copolymer Composition and Nanoparticle Shape
The coassembly of A–B diblock copolymers with B′-type nanoparticles (i.e., nanoparticles that are slightly incompatible with the B domain) leads to hierarchical structures, where the block copolymer phase separates first and the nanoparticles create close-packed arrays within the B domains due to a slower, secondary phase separation process. Here we report the results of a comprehensive study, which focused on two aspects: the influence of the nanoparticle shape (spherical vs rod-like) and the effect of the volume composition of the blocks. Three polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymers featuring similar molecular weights but differing in PS volume fraction were mi…