Intramolecular screening of crystal fields and the X-ray-photoemission determination of charge transfer in TTF-TCNQ

A recent controversy concerns the XPS data for TTF-TCNQ, which shows two binding energies for the N-1s level. We show that XPS chemical shifts due to charge flow on TCNQ, in response to the crystal potential, can cancel the Madelung splitting of the N-1s levels. Then we decompose the N-1s spectrum into its two components, which have widths characteristic of N-1s in TCNQ0 and TCNQ-, and whose intensities suggest charge transfer of ∼ 0.56-0.67. © 1976.