Regensburg 2007 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 46: Poster 2
HL 46.3: Poster
Donnerstag, 29. März 2007, 15:00–17:30, Poster A
Infrared spectroscopy on rotor-stator compounds C60-C8H8 and C70-C8H8 under pressure — •K. Thirunavukkuarasu1, C.A. Kuntscher1, Gy. Bényei2, I. Jalsovszky2, G. Klupp3, K. Kamarás3, É Kováts3, and S. Pekker3 — 1Experimentalphysik II, Universität Augsburg, D-86159 Augsburg, Germany — 2Department of Organic Chemistry, Eötvös Loránd University, P.O.Box 32, Budapest, Hungary H 1518 — 3Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O.Box 49, Budapest, Hungary H 1525
The fullerene-cubane molecular crystals C60-C8H8 and C70-C8H8 are the first members of the rotor-stator crystal family [1]. Static C8H8 molecules occupy the octahedral voids of the fullerene fcc structure and act as bearings for the rotating fullerene molecules. On cooling, C60-C8H8 undergoes an orientational ordering phase transition at 140 K, while C70-C8H8 undergoes transitions at around 390 K and 150 K. Under pressure C60-C8H8 shows orientational ordering at 0.8 GPa [2]. We performed further pressure-dependent transmittance measurements on both C60-C8H8 and C70-C8H8 molecular crystals over a broad frequency range (FIR-VIS), for pressures up to 10 GPa. The pressure-induced changes in the vibrational modes of the fullerene and cubane molecules and the shift of the band gap are reported.
Supported by the DFG.
[1] S. Pekker et al., Nature Materials 4, 764 (2005).
[2] C. A. Kuntscher et al., Phys. Stat. Sol. (b) 243, 2981 (2006).