The C=C Stretching Vibrations of k-(BEDT-TTF)₂Cu[N(CN)₂]Br and Its Isotope Analogues

الأصل · EN

The C=C stretching modes in resonance Raman spectra and infrared reflectivity were measured at temperatures between 15 K and 300 K using various polarizations in k-(BEDT-TTF)₂Cu[N(CN)₂]Br, its fully and partially deuterated analogues, and ¹³C-substituted analogue. The infrared- and Raman-active bands were re-assigned based on the factor group analysis. We found a Raman-active EMV-coupled ν₃ mode near 1420 cm₋₁, which shows a large downshift and broadening through the inter-dimer EMV interaction. The mixing of the bridge and ring C=C stretching vibrations depends upon the symmetry of the crystal mode. In contrast to deuterated crystals, the non-deuterated crystals show a splitting in the ν₂, ν₃, and ν₂₇ bands.