Figure 1

Calculated and measured band profiles in the directional fine structure of white x-ray absorption. (a) Shape of bands calculated using a realistic energy spectrum for absorbing atoms placed at different positions relative to lattice planes. The positions are shown next to the plots and $d$ is the lattice plane spacing. The two upper plots show the two possible symmetrical configurations, whereas the bottom plot shows an asymmetric one. The window functions $w^{+}$ (solid line) and $w^{-}$ (dashed line) used for data evaluation are superimposed on the model curves. (b) Functions arising in the projection integrals calculated for bands shown in (a): $g^{+}(x)$ (top) and $1/x*g^{-}(x)$ (bottom). Dash-dotted lines show zero levels. (c) Top curve: Measured integrated intensity of $(11\overline{1})$ band (solid circles, GaP A side; open squares, GaP B side). Bottom: the difference of the two experimental curves.Reuse & Permissions

Figure 2

Directional fine structure of white x-ray absorption recorded in the experiment. (a) Pattern recorded for GaP B sample. Each point in the pattern corresponds to a given orientation of the sample relative to the x-ray beam. The whole pattern is presented as a stereographic projection. The intensity is normalized to the slowly varying background. The visible bands correspond to real-space projections of the lattice planes. (b) Stereographic projection of the zinc blende structure. The lines are geometrical projections of lattice planes.Reuse & Permissions

Figure 3

Electron density of GaP directly restored from experimental data with the tomographic algorithm. (a) Three-dimensional view. Each voxel is represented as a small bubble with radius and color proportional to $\rho (\mathbf{r})$. The edges of the box are parallel to $⟨001⟩$ directions. The axis ticks are separated by $a_0/2$. (b) Electron density profile along unit cell diagonal. Solid and dashed lines show the positions of Ga and P atoms, respectively.Reuse & Permissions