Charge-Transfer-Induced Isomerization of DCNQI on Cu(100)

Abstract

This article reports on the temperature-controlled irreversible transition between the two isomeric forms of the strong electron acceptor dicyano-pquinonediimine (DCNQI) on the Cu(100) surface. A combination of experiment (time-resolved, variable-temperature scanning tunneling microscopy, STM) and theory (density functional theory, DFT) shows that the isomerization barrier is lower than in the gas phase or solution due to the fact that charge transfer from the substrate modifies the bond configuration of the molecule, aromatizing the quinoid ring of DCNQI and enabling a more free rotation of the cyano groups with respect to the molecular axis.