PNNL

Abstract

We report for the first time the structural, vibrational, and optical properties of americium formate (Am(CHO2)3) crystals synthesized via the in situ hydrolysis of dimethylformamide (DMF). The coordination polymer features Am3+ ions linked by formate ligands into a 3-dimensional network that is isomorphous to several lanthanide analogs, (e.g. Eu3+, Nd3+, Tb3+) . Structure determination revealed a nine-coordinate Am3+ metal center which features a unique C3v symmetry. The ionic bond character of the metal-ligand interactions were investigated using infrared spectroscopy measurements, naturally localized molecular orbitals (NLMO) calculations, and the Quantum Theory of Atoms in Molecules (QTAIM). The optical properties were probed using diffuse reflectance and photoluminescence spectroscopies and also paint an ionic bond picture. Notably, we observe the rarely reported 5D1' ? 7F1' emission band which atypically goes on to dominate the emission spectrum. This behavior is unusual and is attributed to the unique symmetry environment of the metal center.