Proton Irradiation Effect on CdSe-ZnS Core-Shell Nanocrystals Embedded in Ultra Violet Curable Resin

This work focuses on investigating the effect of proton irradiation on the optical properties of CdSe-ZnS core-shell nanocrystals embedded in ultra-violet curable resin. The excitonic transitions were measured using optical absorbance and photoluminescence (PL) techniques. Nanocrystals of three different diameters, 4.5nm, 2.7nm and 2.1nm were used which showed the first exciton peak at wavelengths 600nm, 552nm and 498nm respectively. These samples were subjected to 2MeV protons at different fluence levels. The optical absorbance spectra were collected after the exposure to protons. The integrated area of excitonic transition was monitored as a function of proton fluence. The results indicate that for 4.5nm nanocrystals, the proton irradiation doses up to 9.03 x 10¹⁵ protons-cm^-2 had little effect on the excitonic transitions. However radiation-related degradation seemed to increase with the decreasing size of nanocrystals. No excitonic transition was observed in 2.1 nm nanocrystals from the fluence of 6 x 10¹⁵ protons-cm^-2. This seems to be due to the probable degradation in the resin with the increasing proton fluence. Photoluminescence (PL) measurements were also conducted on 4.5nm nanocrystals using Bomem FT spectrometer. The excitonic transitions were measured at 300K and 77K and small degradation has been observed as understood from the decreasing integrated area with the increasing proton fluence.