10.1021/jp909466b.s002 Marcelo Alves-Santos Marcelo Alves-Santos Rosa Di Felice Rosa Di Felice Guido Goldoni Guido Goldoni Dielectric Functions of Semiconductor Nanoparticles from the Optical Absorption Spectrum: The Case of CdSe and CdS American Chemical Society 2010 spectroscopic data data sets CdSe bulk dielectric function absorption spectrum NP dielectric function Dielectric Functions absorption spectra absorption edge energy range Semiconductor Nanoparticles Optical Absorption Spectrum CdS NPs iterative procedure semiconductor nanoparticles 2010-03-11 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Dielectric_Functions_of_Semiconductor_Nanoparticles_from_the_Optical_Absorption_Spectrum_The_Case_of_CdSe_and_CdS/2785183 We propose a new method to extract the complete size-dependent complex dielectric function ε(<i>E</i>) of semiconductor nanoparticles (NPs) from spectroscopic data. Typical experimental absorption spectra are available in a limited energy range near the absorption edge. We show that this limitation can be overcome by matching the NP dielectric function with the bulk dielectric function at high energies beyond the experimental range. Thus, using the Kramers−Krönig relations that link the real and imaginary parts, it is possible to extract the complete ε(<i>E</i>) of the NP. This is achieved through an iterative procedure that systematically improves the trial ε(<i>E</i>) until the absorption spectrum of the NP is accurately reproduced in the experimental range. Here we describe the methodology and we obtain the ε(<i>E</i>) of CdSe and CdS NPs of selected sizes from published data sets.