K-edge XANES of substitutional and interstitial Mn atoms in (Ga,Mn)As
  This work reports theoretical and experimental study of the X-ray absorption near-edge structure (XANES) at the Mn K-edge in (Ga,Mn)As diluted magnetic semiconductors. The spectra have been calculated from the first-principles using FLAPW including the core-hole effect, a special attention has been paid to consequences of coexistence of Mn impurities in substitutional and tetrahedral interstitial positions. We have performed quantitative component analysis of experimental spectra collected on the (Ga,Mn)As samples before/after annealing and etching, with the aim to determine the proportion of Mn impurity configurations. Comparison of the experimental data with theoretical computations indicates that even after annealing and etching some Mn atoms still reside in interstitial sites, although the concentration of interstitial defects has been reduced by annealing. 
N. A. Goncharuk, L. Smrcka, J. Kucera, K. Olejnik, V. Novak, Z. Matej,   L. Nichtova, V. Holy