Using polarization-dependent $\mathrm{V}2p$ and $\mathrm{O}1s$ near-edge x-ray absorption spectroscopy, we studied the unoccupied electronic structure of single-crystalline ${\mathrm{}\left(\mathrm{VO}\right)\mathrm{}}_2{\mathrm{P}}_2{\mathrm{O}}_7.$ It is highly anisotropic, and shows similarities to vanadium oxides like ${\mathrm{VO}}_2$ and ${\mathrm{V}}_2{\mathrm{O}}_5$ at the $\mathrm{V}2p$ edge and at the $\mathrm{O}1s$ threshold. The contributions from V-O and P-O orbitals could be identified. The results rule out the spin ladder model for the magnetic behavior of ${\mathrm{}\left(\mathrm{VO}\right)\mathrm{}}_2{\mathrm{P}}_2{\mathrm{O}}_7,$ but are consistent with the alternating chain scenario.

• Received 16 August 2000

DOI:https://doi.org/10.1103/PhysRevB.63.073103