UHV-ESR INVESTIGATION OF NO2 AU(111)

The adsorption of NO2 on a clean Au(111) surface has been studied usin g electron spin resonance (ESR) and thermal programmed desorption (TPD ). NO2/Au(111) appears to be an appropriate system in which to detect an ESR Signal, because it is known from the literature that NO2 adsorb s as a molecule and is bonded through its oxygen atoms to the surface, while the spin is more localized at the nitrogen atom. In agreement w ith former results, no resonance of a paramagnetic monolayer on a clea n single-crystal metal surface is observed. However, a well resolved s pectrum from a multilayer has been detected. Orientation of the molecu les in the multilayer has been studied via angle-dependent measurement s in combination with computer simulation. Temperature-dependent measu rements are used to investigate reactivity and molecular motion.