Characterization of charge transfer excitations in hexacyanomanganate(III) with Mn K-edge resonant inelastic x-ray scattering

• Published in: The Journal of chemical physics 2010-04, Vol.132 (13), p.134502-134502-8
• Main Authors: Meyer, Drew A., Zhang, Xuena, Bergmann, Uwe, Gaffney, Kelly J.
• Format: Article
• Language: English
• Subjects: ABSORPTION; ABSORPTION SPECTROSCOPY; ALKALI METAL COMPOUNDS; ATOMIC AND MOLECULAR PHYSICS; BOSONS; CALCULATION METHODS; COHERENT SCATTERING; DENSITY FUNCTIONAL METHOD; DIFFRACTION; ELECTROMAGNETIC RADIATION; ELECTRONIC STRUCTURE; ELEMENTARY PARTICLES; ELEMENTS; EMISSION SPECTRA; ENERGY RANGE; ENERGY TRANSFER; ENERGY-LEVEL TRANSITIONS; EV RANGE; EXCITATION; HARD X RADIATION; HOLES; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IONIZING RADIATIONS; LIGANDS; MANGANESE COMPOUNDS; MASSLESS PARTICLES; METALS; PEAKS; PHOTONS; POTASSIUM COMPOUNDS; RADIATIONS; RAMAN SPECTRA; RESONANCE; SCATTERING; SORPTION; SPECTRA; SPECTROSCOPY; TRANSITION ELEMENT COMPOUNDS; VARIATIONAL METHODS; X RADIATION; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.3367958

We use hard x-ray resonant inelastic x-ray scattering (RIXS) and density functional theory (DFT) calculations to characterize charge transfer excitations in K 3 Mn ( CN ) 6 . The combination of RIXS measurements and DFT calculations allows us to characterize the strength of the ligand-metal electronic interaction and assign the Raman resonances in the RIXS spectra to charge transfer excitations. With x-ray excitation energies resonant with the T 2 g and E g pre-edge peaks derived predominantly from the Mn 3 d orbitals, we observe Raman resonances in the energy transfer range from 2 to 12 eV, which results from the filling of the 1 s core-hole from T 1 u -symmetry occupied orbitals. DFT calculations indicate that these orbitals exhibit primarily ligand character, supporting the assignment of the energy transfer resonances to ligand-to-metal charge transfer excitations. Our RIXS measurements and DFT calculations also indicate that the E g -orbital spin-splits by roughly 0.8 eV, though we do not cleanly resolve the two absorption peaks in the RIXS spectra. We also see evidence for a metal-to-ligand charge transfer (MLCT) excitation when exciting with a 6545.0 eV incident photon, roughly 4 eV above the E g absorption peaks. The 6545.0 eV resonant emission spectrum shows a 6.0 eV energy transfer resonance, which corresponds to a final state hole in the T 2 g partially occupied orbital. DFT calculations indicate that excitation at 6545.0 eV populates an unoccupied T 1 u -symmetry orbital of primarily ligand character. Given the predominantly metal character of the final state hole, we assign the 6.0 eV Raman resonance to a MLCT excitation. These measurements demonstrate the ability of hard x-ray RIXS to characterize the valence electronic structure of coordination compounds.