Raman and FTIR studies of phase transitions in the organic superconductor kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl

The Raman active C=C stretching modes and CH, deformation modes and the inf rared active CN mode are studied as a function of temperature in kappa-(BED T-TTF)(2)Cu(N(CN)(2))Cl under pressure. Effects of the structural and super conducting transitions on these excitations are analyzed. The CH2 and CN mo des are sensitive to the thermal expansion around 80 K and to a possible su perlattice transition around 160 K while the C=C stretching Raman modes nu( 2)(A(g)) are influenced by the formation of the superconducting state. (C) 1999 Elsevier Science S.A. All rights reserved.