Berlin 2015 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 66: Low-Dimensional Systems: Molecular Conductors (joint session with CPP, HL, MA, O)

CPP 66.2: Vortrag

Donnerstag, 19. März 2015, 09:45–10:00, H 3010

Observation of charge localization and the charge ordering transition in (TMTTF)2AsF6 using NEXAFS — •Katerina Medjanik1, Alisa Chernenkaya2, Sergej Nepijko2, Gunnar Öhrwall1, Pascale Foury-Leylekian3, Pere Alemany4, Enric Canadell5, Gerd Schönhense2, and Jean-Paul Pouget31Lund University, MAX IV Laboratory, 22100 Lund, Sweden — 2Institut für Physik, JOGU, 55099 Mainz, Germany — 3Laboratoire de Laboratoire de Physique des Solides, Université Paris-Sud, 91405 Orsay, France — 4IQTCUB, Universitat de Barcelona, 08028 Barcelona, Spain — 5ICMAB-CSIC, 08193 Bellaterra, Spain

High-resolution near-edge X-ray absorption fine structure (NEXAFS) measurements at MAX II, Lund (beamline I1011 [1]) were performed on a (TMTTF)2AsF6 [2] single crystal upon cooling from room temperature to 90 K. Systematic shifts of different spectral features of the F 1s and S 2p signal by up to 0.8 eV to opposite sides on the photon-energy scale with respect to the spectra at room temperature have been detected. Most likely, the shift of the S 2p signal is connected with the breakdown of itinerant conductivity and loss of screening when entering the charge-localization regime.The appearance of a new F 1s pre-edge signal upon entry into the charge ordering (CO) phase at 90 K is a clear fingerprint of the reorganization of the anions in the layered material and changing in the dimerization of molecular orbitals with respect to room temperature.Project funded by DFG through SFB Transregio 49.

[1] I. A. Kowalik et al., J. Phys.: Conf. Ser. 211, 012030 (2010);

[2] M. de Souza et al., Physica B, 405, 92 (2010).

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