ELECTRON-PHONON INTERACTION IN THE ORGANIC SUPERCONDUCTORS ALPHA(1)-(BEDT-TTF)(2)I-3 AND BETA-(BEDT-TTF)(2)IAUI

A study of the low energetic modes in the resonance Raman spectra of t he organic superconductors alpha(t)-(BEDT-TTF)(2)I-3 (T-c=8 K) and bet a-(BEDT-TTF)(2)IAuI (T-c=4 K) in the temperature range of 1.5 K-100 K was performed. In both materials, a vanishing of low energetic phonon bands (at 32 cm(-1) and 42 cm(-1) for alpha(t)-(BEDT-TTF)(2)I-3 and at 27 cm(-1) and 33 cm(-1) for beta-(BEDT-TTF)(2)IAuI) is observed below T-c. For the symmetric stretching mode of the I-3(-)-Anions at 120 cm (-1), no change below T-c was found. The vanishing of the phonon bands is explained in the Balseiro-Falicov model of phonon-superconducting amplitude mode interaction due to a strong interaction of the supercon ducting gap and some phonon modes. In addition, measurements on alpha- and kappa-(BEDT-TTF)(2)I-3 are presented, indicating that the vanishi ng modes around 30 cm(-1) are librational modes of the BEDT-TTF molecu les.