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Intramolecular phonons of the {beta} and {beta}* phases of the unlabeled and {sup 13}C-labelled (BEDT-TTF){sub 2}I{sub 3} organic superconductor above and near {Tc}

Conference ·
OSTI ID:538213
; ; ; ;  [1];  [2]
  1. Inst. des Materiaux, Nantes (France)
  2. Univ. de Paris-Sud, Orsay (France). Lab. de Physique des Solides
The authors present a temperature dependence investigation of the C{double_bond}C intramolecular phonon for both the normal and inter-ring C*{double_bond}C* labelled salts (BEDT-TTF){sub 2}I{sub 3} superconducting at {Tc} = 1.5 K and 8 K. C{double_bond}C bond frequencies are found at 1467, 1493 cm{sup {minus}1} and 1420, 1488 cm{sup {minus}1} for the unlabeled and labelled crystals, respectively. They have also computed the infrared and Raman frequencies of the unlabeled and labelled BEDT-TIF molecules. In the low frequency range they found in special operating conditions a triiodide I{sub 3{sup {minus}}} line at 106 cm{sup {minus}1} in addition to those found at 36, 116, and 146 cm{sup {minus}1}. At 8 K the Raman profile of the intense triiodide line at 116 cm{sup {minus}1} can hardly be fitted with a Lorentzian. On the other hand, they also did not succeed to fit correctly the low temperature profile of the inter-ring C{double_bond}C line with a single Lorentzian; however Fano line shapes gave satisfactory fits. Taking into account that recent results of Kini, Ferraro and Williams provided evidence of participation of lattice phonons in the pairing mechanism, the results show that intramolecular C{double_bond}C vibrations must also be considered as a possible mediation factor for superconductivity.
OSTI ID:
538213
Report Number(s):
CONF-960163--; ISBN 0-8194-2070-0
Country of Publication:
United States
Language:
English