X-ray Photoelectron and Raman Spectra of TMTTF-TCNQ: Estimation of the Valence Fluctuation Time and the Degree of Charge Transfer

The X-ray photoelectron and Raman spectra of quasi one-dimensional conductor TMTTF-TCNQ were measured at room temperature. A combined analysis of N 1 s (or S 2 p ) core level XPS spectra and Raman spectra is shown to give a characteristic time scale (τ∼10 -14 sec) of valence fluctuation in this mixed-valence complex. From the Raman frequency of TCNQ ν 4 band, the degree of charge transfer in TMTTF-TCNQ is given to be 0.50±0.05, which is smaller than that in TTF-TCNQ and is close to a commensurate value.