Fluorescence Mode XANES Spectroscopy as a Powerful Tool for Redox-Isomerism Studies in Ultrathin Films

Redox-isomerism, i.e., intramolecular electron transfer that results in isostructural compounds with different charge distribution between metal center and ligands, and thus in their different physico-chemical characteristics, attracts considerable interest from the standpoint of development of novel molecular devices. However, direct determination of the valence states of the coordinating cations remains an urgent task. In the present work on the example of cerium bis-tetra-15-crown-5-phthalocyaninate it was shown that synchrotron source X-ray absorption near edge structure spectroscopy in fluorescent mode is a powerful method that allows to directly observe valence states of the metal cations in redox-isomeric materials even in ultrathin single-layer Langmuir-Blodgett films, which are notably hard to study due to extremely small amounts of matter and low dimensionality