ANOMALOUS ENHANCEMENT OF G-SHIFT IN KAPPA-TYPE BEDT-TTF COMPOUNDS

Systematic investigation of the ESR properties of K-type BEDT-TTF comp ounds has been carried out. The salts with crystal symmetry of P2(1), kappa-Cu(NCS)(2)(#), kappa-Cu(CN)[N(CN)(2)] and kappa-Ag(CN)(2) . H2O, were found to show an anomalous enhancement of g-shift below about 13 0K when the static field was applied along b axis. Concomitantly, abru pt broadening of the linewidth has been observed in all principal axes . On the other hand, kappa-Cu[N(CN)(2)]Br (Pnma) and kappa'-Cu-2(CN)(3 ) (P2(1)/c) have almost temperature independent g-values for all field directions. We discuss the possible explanation of the anomalous enha ncement of the compounds with P2(1) space group.