Luminescence study of bare and coated CdS quantum dots: Effect of SHI irradiation and ageing
Bare and silica coated CdS quantum dots are prepared following chemical route. Swift heavy ion (SHI) irradiation of the samples was carried out with 160 MeV Ni 12+ ion beam with fluences 10 12 –10 13 ions/cm 2 . Photoluminescence (PL) studies of all the samples were carried out with excitation wavelength 325 nm. The surface state emission is dominant in case of bare samples while e–h recombination is observed in case of coated samples. Red shift in the absorption response in the optical absorption spectra of bare samples reveal size enhancement of the quantum dots after irradiation. No such shift is observed for coated samples. The coated samples also exhibit enhanced photo stability. � 2005 Elsevier B.V. All rights reserved.
The dependence of the differential cross section ${\mathrm{d}\sigma}/{\mathrm{d}p_{\perp}}$ of inclusive heavy quark production in pp and $\bar{\mathrm{p}}$p collisions on the renormalization and factorization scales is investigated. The implications of our results for experiments at TEVATRON and LHC are discussed. In particular, it is shown that the NLO QCD predictions for $\bar{t}t$ production at the LHC based on the Principle of Minimal Sensitivity are by 30-50% higher than the standard ones.