Nuclear-Magnetic-Resonance Studies on 23Na Atoms Chemisorbed on Various W Single-Crystal Surfaces

Nuclear-magnetic-resonance (NMR) experiments at 23Na atoms chemisorbed on hot W(110), W(100) and W(112) surfaces were performed using nuclear-spin-polarized Na atomic beams impinging on the surfaces under investigation. The nuclear-spin polarization of the desorbing atoms was observed by laser-induced fluorescence as a function of the frequency of an external r.f.-field. The experiments show clear sensitivity of the electric-field gradient tensors to the surface structure itself and to coadsorption.