The geometric and electronic local structure of LaMnO 3 across the cooperative Jahn-Teller (JT) transition at T JT = 750 K has been studied by means of Xray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) at the Mn K-edge. XANES spectra, as a function of temperature, do not show significant changes either in the pre-peak structures or at the absorption edge indicating similar electronic local structure for the Mn atom above and below T JT . Analysis of the EXAFS spectra shows that dynamical tetragonal JT distortion of the MnO 6 octahedron is also present above T JT . The structural transition is explained in terms of an orientated ordering of tetragonal distorted octahedral complexes. Above T JT , the e g electron jumps between the three degenerate vibronic states being localized and ordered below the transition.

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