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V(TCNE)<sub>x</sub>: the electronic structure of an enigmatic, organic-based room temperature magnet revealed
Manuscript (preprint)
Carl Tengstedt, M. P. de Jong, Anna Kanciurzewska, Elin Carlegrim, William R. Salaneck, Mats Fahlman
Publication Year

<p>We have prepared and characterized thin films of V(TCNE)<sub>x</sub> in ultra-high vacuum using a novel film growth technique based on <em>in-situ</em> chemical vapor deposition of tetracyanoethylene, TCNE, and <em>bis</em>-benzene vanadium, V(C<sub>6</sub>H<sub>6</sub>)<sub>2</sub>. The <em>in-situ</em> preparation method enabled, for the first time, experimental analysis of the electronic structure. X-ray magnetic circular dichroism (XMCD) measurements recorded at the V L<sub>2,3</sub>-edge confirmed room temperature magnetic ordering. A combination of conventional photoelectron spectroscopy (PES) and resonant photoemission (RPE) measured at the x-ray absorption edges (V L<sub>3</sub>-edge, C K-edge, N K-edge) shows that the highest occupied electronic state is V(3d)-derived. Nearly complete quenching of the V(3d) orbital angular momentum is observed from the low value of the integrated XMCD signal, indicating a strong ligand field. The rearrangements of the TCNE" related valance electronic states observed in PED and near edge x-ray absorption fine structure (NEXAFS) spectra, in combination with the evidence of V(3d) and TCNE" π (π<sup>*</sup>) orbital overlap contained in RPE spectra, also point to strong, covalent type bonding.</p>