J. Phys. I France
Volume 6, Numéro 12, December 1996
Page(s) 1631 - 1641
DOI: 10.1051/jp1:1996179
J. Phys. I France 6 (1996) 1631-1641

Polarized IR Reflectance Studies of the Organic Conductor $\mathsf k$-(BETS) $\mathsf{_2}$FeCl $_\mathsf 4$

I. Olejniczak1, A. Graja1, N.D. Kushch2, P. Cassoux3 and H. Kobayashi4

1  Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan, Poland
2  Institute of Chemical Physics, Russian Academy of Sciences, 142 432 Chernogolovka, Russia
3  Equipe Précurseurs Moléculaires et Matériaux, LCC/CNRS, 205 route de Narbonne, 31077 Toulouse Cedex, France
4  Department of Chemistry, Faculty of Sciences, Toho University, Funabashi, Chiba 274, Japan

(Received 8 March 1996, revised 4 June 1996, accepted 13 August 1996)

The infrared and Raman spectra of neutral bis(ethylenedithio)tetraselenafulvalene (BETS) as powder sample is reported. An assignment of the fundamental vibrational modes is presented and discussed; the vibrations are assigned using correlations between the obtained data and those for similar compounds: BEDT-TTF and BEDO-TTF. The results are used for analysis of absorption spectra and microreflectance polarized IR spectra of single crystal k-(BETS) 2FeCl 4. The vibrational features of the spectra have been essentially assigned to a mixture of normally-inactive totally-symmetric A $_{\rm g}$ modes and IR-active modes of other symmetries. A general discussion of the origin of the electronic bands is given also. To our knowledge, the first spectral investigation of BETS and its salt are presented in this paper.

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