ABSTRACT
The effect of additives on the photostability of semiconductor nanoparticles was studied using CdSe, CdSe/ZnSe and CdSe/ZnS particles of various sizes and composition. The additives included phosphine oxides, amines, and antioxidants. Strong initial enhancement of band edge emission by hexadecylamine was observed for the uncoated particles but stability over a week period in light and air was shown to be poor. Inorganic coatings rendered the nanoparticles initially insensitive to additive but provided little extra stability in terms of photoluminescence. Antioxidant was shown to be effective at reducing the rate of photooxidative degradation for all particles in chloroform but not in toluene.
Subject(s)
Amines/chemistry , Antioxidants/chemistry , Nanostructures/chemistry , Oxides/chemistry , Adsorption , Cadmium Compounds/chemistry , Chloroform/chemistry , Particle Size , Phosphines/chemistry , Photochemistry , Quantum Theory , Selenium Compounds/chemistry , Semiconductors , Solutions/chemistry , Solvents/chemistry , Sulfides/chemistry , Surface Properties , Zinc Compounds/chemistryABSTRACT
Circular dichroism (CD) is the difference in absorption of left and right circularly polarized light, usually by a solution containing the molecules of interest. A signal is only measured for chiral molecules such as proteins. A CD spectrum provides information about the bonds and structures responsible for this chirality. When a small molecule (or ligand) binds to a protein, it acquires an induced CD (ICD) spectrum through chiral perturbation to its structure or electron rearrangements. The wavelengths of this ICD are determined by the ligand's own absorption spectrum, and the intensity of the ICD spectrum is determined by the strength and geometry of its interaction with the protein. Thus, ICD can be used to probe the binding of ligands to proteins. This chapter outlines protein CD and ICD, together with some of the issues relating to experimental design and implementation.
