Chemical change of nitrosylpentacyanoferrate(II) during XPS measurements: Identification of the irradiated product by DV-Xα molecular orbital calculations

Abstract

A spectral change of the core and valence band levels for sodium nitrosylpentacyanoferrate(II) dihydrate, Na₂[Fe(NO)(CN)₅]· 2H₂O, has been observed during XPS measurements. The fresh sample had two peaks for N 1s at 402.9 and 398.8 eV, one peak for Fe 2p_3/2 at 710.6 eV and one peak for Fe 2p_1/2 at 723.5 eV. The irradiation of the sample by X-ray and e⁻ flood decreased the intensity of the N 1s signal at 402.9 eV, and gave new peaks in 708.4 and 721.5 in the Fe 2p region. Irradiation also gave a peak of 1.5 eV in the valence band. The experimental results and a molecular orbital calculation by the DV-Xα SCF procedure suggest that the irradiated product of the compounds is [Fe(CN)₅]³⁻ or [Fe(CN)₅(OH₂)]³⁻.