Spectroscopic Investigations of the Surface-Level Interaction of Europium (III) Ions and Polyaniline Particles

We investigated the surface-level interaction of the Eu³⁺ ions with polyaniline (PANI-EB) particles prepared by using liquid-phase impregnation method with formation of PANI/EuCl₃ complex hybrid structure. Scanning electron microscopy (SEM) confirmed that the micro-sized PANI-EB particles possess a porous, granular structure. X-ray photoelectron spectroscopy (XPS) revealed the Eu³⁺ ions interaction with the imine and amine groups of the PANI-EB. The Raman and FTIR spectra analysis are consistent with interaction between PANI-EB and EuCl₃ with formation of the Eu-N bonds. Under UV excitation, the base PANI-EB polymer emission at 420 nm is accompanied by the characteristic red luminescence peaks of Eu³⁺ ions, albeit with a relatively low efficiency of approximately 4%. These results indicate the formation of a PANI/EuCl₃ complex hybrid structure at the particle surface; its luminescent properties are attributed to a surface-mediated energy transfer within the complex via the "antenna effect".