EXPERIMENTAL-DETERMINATION OF BEDT-TTF-MOLECULAR VIBRATION CONSTANTS THROUGH OPTICAL MICROREFLECTANCE( ELECTRON)

In the salt formed by bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with the [Mo6O19](2-) anion, the BEDT-TTF+ cations form quasi-isolate d dimers. For this reason (BEDT-TTF)(2)Mo6O19 has been selected to exp erimentally evaluate the BEDT-TTF+ microscopic parameters. Using the m icroreflectance technique we were able to collect polarized infrared/v isible spectra from a single-crystal face. The analysis of the spectra in terms of the isolated dimer model yields reliable estimates of BED T-TTF+ electron-molecular vibration (e-mv) coupling constants. The eff ective on-site electron-electron repulsion is also evaluated. A compar ison is made with available theoretical estimates of e-mv coupling con stants. The possible role of e-mv coupling in BEDT-TTF based supercond uctors is briefly discussed. [S0163-1829(98)01738-X].