Mixed valence of a delocalized system: a resonance Raman study of the tetracyanoquinodimethane radical anion

摘要

The optical absorption spectrum and resonance Raman enhancement of the lowest energy absorption band of K(+)7,7,8,8-tetracyanoquinodimethane(-) (TCNQ) are reported and examined in the mixed valence (MV) framework. The absorption spectrum is assigned, in accordance with previous work, using Koopmans-based calculations and the neighboring orbital model is constructed from the adiabatic orbital energies. Calculated fits of the lowest energy absorption band and the corresponding resonance Raman enhancement profiles are made using the time-dependent theory of spectroscopy.