ELECTRONIC AND ELECTRONIC-VIBRATIONAL PHENOMENA IN THE NEW ORGANIC CONDUCTOR KAPPA-(ET)(2)[HG(SCN)(2)CL] WITH A METAL-INSULATOR-TRANSITION

The reflection spectra and optical conductivity spectra of the new org anic conductor kappa-(ET)(2)[Hg(SCN)(2)Cl] with a metal-insulator tran sition in the spectral regions 700-5500 and 9000-40 000 cm(-1) have be en studied in polarized light at 300 K. A comparisonis made between th e spectra obtained and the corresponding spectra of related isostructu ral conductors based on the ET molecule, and also the properties of th e crystal structure of the investigated compounds. An electronic trans ition between the ET molecules of the dimer (ET)(2)(+) in the spectral region 700-5500 cm(-1) has been identified, as have the features of t he electronic-vibrational structure arising as a consequence of the in teraction of this transition with the completely symmetric intramolecu lar vibrations of the ET molecule. It is found that the conductor with the stronger dimer interaction between the ET molecules has the highe r the transition temperature. (C) 1997 American Institute of Physics.