NEXAFS INVESTIGATIONS OF HIGHLY-ORDERED ULTRATHIN FILMS OF DME-DCNQI ON AG(111)

Ultrathin layers of 2,5-dimethyl-N,N'-dicyanoquinonediimine (DMe-DCNQI ) have been grown on a Ag (111) surface by vapour deposition in ultrah igh vacuum. The films have been characterized by near-edge X-ray absor ption fine structure (NEXAFS), low-energy electron diffraction (LEED), Thermal desorption measurements and X-ray photoelectron spectroscopy to study orientation, lateral order, interface bonding, and electronic structure. On the clean Ag(111)-surface the DMe-DCNQI molecules adsor b in parellel orientation in the monolayer regime as well as for thick er layers up to thicknesses of more than 10 nm as proved by NEXAFS. Fo r the first two layers a LEED pattern is observed indicating high late ral order in the interface. In addition, films of two radical ion salt s, Cu(DMe-DCNQI)(2) and Na(DMe-DCNQI)(2), were prepared by subsequent evaporation of DMe-DCNQI and metal counterions and by annealing, The r edox reaction strongly affects the fine structure in the NEXAFS spectr a of DMe-DCNQI which correlates with a strong admixture of metal orbit als.