Experimental Determination of the Extinction Coefficient of CdTe, CdSe, and CdS Nanocrystals

Abstract

The extinction coefficient per mole of nanocrystals at the first exitonic absorption peak, ε, for high-quality CdTe, CdSe, and CdS nanocrystals was found to be strongly dependent on the size of the nanocrystals, between a square and a cubic dependence. The measurements were carried out using either nanocrystals purified with monitored purification procedures or nanocrystals prepared through controlled etching methods. The nature of the surface ligands, the refractive index of the solvents, the PL quantum yield of the nanocrystals, the methods used for the synthesis of the nanocrystals, and the temperature for the measurements all did not show detectable influence on the extinction coefficient for a given sized nanocrystal within experimental error.

Inorganically Functionalized PbS–CdS Colloidal Nanocrystals: Integration into Amorphous Chalcogenide Glass and Luminescent Properties

“…The initial and final PbS NC core sizes of PbS were determined from the energy of the first absorption peak, 2,3 and were in good agreement with TEM images (for initial PbS) and with ICP-OES analysis (for core-shell dots). …”

Silica-Coated CdTe Quantum Dots Functionalized with Thiols for Bioconjugation to IgG Proteins

“…Upon the basis of the exitonic peak position of 525 nm, an experimental data fitting polynomial predicted a size of 2.89 nm for CdTe nanocrystals. 32 The observed average particle size of ∼4 nm is larger than that predicted based on the exiton position, which could be due to a passivating shell of CdO, the stabilizing molecule TGA, or a tip effect that distorted the z-axis measurements. Figure 8 shows a representative HRTEM image of CdTe QDs with a well-resolved 6 nm nanocrystal next to an amorphous silica particle of approximately 3 nm.…”

Photochemical Fine-Tuning of Luminescent Color of Cadmium Selenide Nanoparticles: Fabricating a Single-Source Multicolor Luminophore

“…The wavelength of the exciton peak was blue-shifted to 516 nm from that of original particles, 553 nm, with photoetching at 560 nm, corresponding to a decrease in CdSe size from 3.1 to 2.5 nm that was estimated from the reported relation between exciton peak position and CdSe size. 23 Photoetched SiO 2 /CdSe (col) was stable without sedimentation for at least several weeks when stored in the dark. This fact indicated that the SiO 2 shell layer surrounding the CdSe core prevented coalescence between the photoetched CdSe particles.…”