Supplementary Information Enhancing the dual magnetic and optical properties of co-doped cerium oxide nanostructures R. Avinash Kumar, K. Suresh Babu, Arup Dasgupta and R. Ramaseshan To correlate the oxidation state modification of the elements with annealing, XPS studies were carried out using Al K α source. The XPS spectra were charge corrected with respect to C 1s peak. The high resolution Ce 3d spectra is shown in Figure S1 for EFCR and EFC9 along with the deconvoluted peaks. The multiple peaks arise after deconvolution due to the presence of cerium in +3 and +4 oxidation states as well as multiple d-splitting. Figure S1: XPS spectra of Ce 3d for EFCR and EFC9 Electronic Supplementary Material (ESI) for RSC Advances. This journal is © The Royal Society of Chemistry 2015