PROBING THE ELECTRONIC-STRUCTURE IN M(2)MO(6)SE(6) - QUADRUPOLE COUPLINGS MEASURED BY NMR

Nuclear-magnetic-resonance spectroscopy has been used to probe the ele ctronic structure of the M cationic sites in M(2)Mo(6)Se(6), M=(Li,Rb, Cs,In), a family of low-dimensional electronic conductors. Measured va lues of the quadrupole coupling parameter constant are compared to cal culated values of the contribution from an ionic lattice. The measured values deviate significantly from calculation only for M=In, where th e observed value substantially exceeds the calculated value. This devi ation is attributed to an In p-orbital contribution to the conduction band. Such a contribution would provide a mechanism for the interchain electronic coupling observed in M(2)Mo(6)Se(6) chain systems when M=I n or Tl.