Spectroscopic evidence for surface anion radical formation of tetracyanoethylene adsorbed on copper(111) at 100 K: a high-resolution electron energy loss study

Abstract

Adsorption of tetracyanoethylene (TCNE) on a Cu(111) single surface at 100 K has been studied by high-resolution electron energy loss spectroscopy. Upon initial adsorption there is spectroscopic evidence for partial fragmentation of TCNE molecules. For increasing coverages up to one monolayer, a multiply charged TCNE ion is identified as the dominant species on the copper surface. Further exposure to TCNE produces vibrational modes characteristic of TCNE anions, most likely adsorbed in a second layer. Finally, multilayer condensation for high exposures is indicated by the observation of virtually all vibrational modes of crystalline TCNE.