Electronic structure of KD2xH2(1-x)PO4 studied by soft x-ray absorption and emission spectroscopies

摘要: The surface and bulk electronic structure of tetragonal (at 300 K) orthorhombic 77 $\mathrm{K}{\mathrm{D}}_{2x}{\mathrm{H}}_{2(1\ensuremath{-}x)}\mathrm{P}{\mathrm{O}}_{4}$ single crystals (so-called KDP DKDP), with a deuteration degree $x$ 0.0, 0.3, 0.6, is studied by soft x-ray absorption near-edge (XANES) emission (XES) spectroscopies. High-resolution $\mathrm{O}\phantom{\rule{0.2em}{0ex}}K$-edge, $\mathrm{P}\phantom{\rule{0.2em}{0ex}}{L}_{2,3}$-edge, $\mathrm{K}\phantom{\rule{0.2em}{0ex}}{L}_{2,3}$-edge XANES XES spectra reveal that the element-specific partial density states in conduction valence bands essentially independent $x$. We give assignment peaks based on previous molecular orbital band-structure calculations. Projected densities band also appear to be identical for phases, consistent However, decrease sample temperature from K results measurable changes (probed XES) but not XANES). lower limit room-temperature gap DKDP estimated as $\ensuremath{\sim}7.6\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. Results show high-intensity irradiation decomposition these hydrogen-bonded materials into water $\mathrm{K}\mathrm{P}{\mathrm{O}}_{3}$ cyclophosphates polyphosphates.