X-ray absorption and emission spectroscopy of ZnO nanoparticle and highly oriented ZnO microrod arrays

• The electronic structures of ZnO nanoparticles and microrod arrays are studied by 0 Is X-ray absorption spectroscopy (XAS) and O K alpha X-ray emission spectroscopy (XES). We show that the present LDA +U-SIC calculation approach is suitable to correct the LDA self-interaction error of the cation d-states. The atomic eigenstates of 3d in zinc and 2p in oxygen are energetically close, which induces strong Zn-3d-O-2p hybridization. This anomalous valence band cation-d-anion-p hybridization is affected when the localization of the Zn 3d-states is taken into account. Experimentally, the XES spectra show energy dependence in the spectral shape revealing selected excitations to the Zn 3d, 4s and 4p states, hybridized with 0 2p states. Strong anisotropic effects are observed for the highly oriented ZnO rods, but not for the isotropic spherical nanoparticles. The nanostructured ZnO has primarily bulk XAS and XES properties.

Nyckelord

ZnO

nanostructure

X-ray

absorption

emission

d-state localization

room-temperature

gan

polarization

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