Influence of the Particle Size on the Optical Properties of CdSe Nanoparticles

Abstract

Monodispersed CdSe nanoparticles with sufficient luminescence intensity have been prepared by chemical method in the presence of mercaptoacetic acid as a capping agent. Cadmium acetate (Cd(Ac) 2 .2H 2 O) and sodium selenosulfate (Na 2 SeSO 3 ) are used as a cadmium and selenium sources respectively. The resulting nanocrystallites have been characterized by X-Ray Diffraction, UV-Vis absorption spectra and photoluminescence (PL) spectroscopy. The particle size was estimated from broadening of XRD peak using Scherrer's formula and also from effective band gap by absorption peak using effective mass approximation model. The size obtained from XRD and absorption peaks are in agreement with each other. It is observed that the samples consist of separated, well-defined spherical particles and show a small size distribution as well as a characteristic blue shift due to quantum confinement in their optical absorption as well as PL spectra. It is found that the size of CdSe nanoparticles decreases, as the concentration of capping agent is increased. The intensity of PL peak increases and the peak shift towards blue region as the particle size is reduced. The sharp PL spectra also indicate that the nanoparticles are monodispersed.

Preparation of Yb2O3 submicron- and nano-materials via electrospinning

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UVA‐shielding silicone/zinc oxide nanocomposite coating for automobile windows

“…The clear peak between 300 and 320 nm is assigned to the electronic transition from top of the valence band to bottom of the conduction band. Since ZnO has a direct band gap, its magnitude can be calculated from the wavelength of the absorption edge using the formula , and hence, the corresponding particle size can be estimated using effective mass approximation (EMA) ; the values are given in Table . There is pronounced enlargement of band gap when compared with bulk ZnO that has an energy gap of 3.37 eV at room temperature, indicating that the particle size is in the quantum regime .…”

Effect of pyrolytic temperature on the properties of TiO2/ITO films for hydrogen sensing

“…4 [32][33][34][35]. However, the spectrum of the film prepared at 250 °C revealed decreased bandwidth with decrease in intensity which can be attributed to the effect of smaller particle size which affects the force constant and vibrational amplitudes of the nearest neighbor bond.…”