For the first time we present NMR-Experiments with Xenon, adsorbed on metallic single crystal surfaces (Ir(111) and Cu(111)). The inherently low sensitivity of NMR could be raised by five orders of magnitude through optical pumping with Rubidium. Large chemical shifts have been obtained, far above the shift range commonly attributed to physisorption. The Knight-Shift (Fermi contact interaction) could clearly be identified as the main reason for the measured shifts.
