Influence of the Fluorination of Iron Phthalocyanine on the Electronic Structure of the Central Metal Atom

The electronic structure of the central Fe ion of iron phthalocyanine (FePc) and perfluorinated iron phthalocyanine (FePcF16) in thin films is investigated by X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD), supported by photoemission. Both molecules grow in a flat-lying adsorption geometry in thin films. Fe L-edge X-ray absorption spectra of FePc and FePcF16 exhibit minor, but distinct, differences of the shape, indicating a different electronic structure. A significantly stronger XMCD signal and thus larger magnetic moments were observed for FePc compared to FePcF16 at low temperatures (15 K). Multiplet calculations have been used to simulate the XA and XMCD spectra and give detailed insight into the electronic structure of Fe in FePc and FePcF16. We suppose that the electronic structure crucially depends on the detailed arrangement of FePc and FePcF16 molecules in thin films.