Are you an EPFL student looking for a semester project?
Work with us on data science and visualisation projects, and deploy your project as an app on top of Graph Search.
Transient changes in the local structure of optically excited Ti3+ ions in a Al2O3 single crystal are studied by time-resolved x-ray absorption spectroscopy. A model considering coupling of the excited E-2(C-3v) electronic state of the Ti3+ ion to the approximate A(1g)(O-h) and E-g(O-h) local vibrational modes of the TiO6 octahedron is constructed to fit the experimental data. We determine the magnitude of the A(1g)(O-h) mode and give an estimate of the E-g(O-h) Jahn-Teller distortion although this analysis does not distinguish between compression and elongation of the oxygen octahedron. Assuming a compressed octahedron, the E-g (O-h) distortion is found to be 0.14 +/- 0.02 angstrom with an A(1g)(O-h) mode of 0.066 +/- 0.006 angstrom. In the case of an elongated octahedron the E-g(O-h) distortion is -0.195 +/- 0.017 angstrom with an A(1g)(O-h) mode of 0.052 +/- 0.002 angstrom.