Method Quantity Maximum- Intensity

Electron energy-loss (EEL) white-lines of transition metals contain rich information on the crystallographic site and the charge state of the excited element [1,2]. In this way, the Mn-L2,3 lines show characteristic changes with Mn valency, among those the ratio of the L3- to the L2-intensity [3,4]. To determine the white-line intensities from experimental EEL spectra four different approaches have been analyzed with focus on their Mn valence sensitivity in the range [Mn3+; Mn4+]. We found that the maximum-intensity as well as Pearson’s [5] and Walsh-Dray [6] methods yield noticeably larger relative ratio changes than curve-fitting (Table 1). As a measure for the Mn valency distinction power the ratio change related to the scattering was evaluated for the curve-fitting and Walsh-Dray methods. According to this measure Walsh-Dray distinguishes more strongly between Mn3+ and Mn4+ (Table 1) and represents therefore the preferred method to analyze the Mn valency in mixed-valency manganites. This research was supported by the Deutsche Forschungsgemeinschaft [7]. Table 1. Change of I(L3) / I(L2) and valence sensitivities (last row) for the analyzed extraction methods; all data refer to a representative spectrum set