J. Phys. IV France
Volume 114, April 2004
Page(s) 87 - 90

J. Phys. IV France
114 (2004) 87
DOI: 10.1051/jp4:2004114016

Phase transition in the organic conductor (TTM-TTP)I 3 studied by infrared and Raman spectroscopies

R. Swietlik1, 2, 1, K. Yakushi2, K. Yamamoto2, T. Kawamoto3 and T. Mori3

1  Inst. Molec. Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznañ, Poland
2  Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
3  Depart. Organic and Polymeric Mater., Tokyo Instit. Technology, O-Okayama, Tokyo, Meguro 152-8552, Japan

Polarised infrared reflectance (600-10000 cm -1) as well as Raman scattering spectra of the organic conductor (TTM-TTP)I 3 were investigated as a function of temperature, below and above the metal-insulator phase transition at T=160 K. The IR electronic dispersion was analysed in terms of a Lorentz model and optical transport parameters were determined. The phase transition at 160 K has nearly no influence on IR spectra. The Raman scattering was studied for different excitations ( $\lambda $ =514.5, 632.6 and 785 nm). Within the C=C stretching region three Raman bands at 1436, 1453 and 1486 cm -1 were found and assigned to the three TTM-TTP modes of a $_{\rm g}$ symmetry. Due to the phase transition the band at 1486 cm -1 splits into two lines at about 1487 and 1500 cm -1. We relate this splitting to an asymmetric deformation of TTM-TTP. Key words. TTM-TTP salt - organic metal - IR and Raman spectra - phase transition.

© EDP Sciences 2004