FOURIER-TRANSFORM NMR AT SINGLE-CRYSTAL SURFACES - LI-6 ON RU(001)

NMR was performed on lithium adsorbates (10(-5) of a monolayer) on a r uthenium single crystal surface. For the first time, free induction de cay and spin echo measurements were performed, yielding the transverse relaxation times T-2 and T-2. The experiments utilize highly polariz ed adsorbates and a new beam-foil detection scheme, with single photon counting and phase coherent summation. A short T-2 time of 17 ms is f ound and contrasted with the much longer T-1 time of 760 ms under cond itions where the adsorbate is highly mobile. The reduced dimensionalit y of the system is the probable cause for this effect. (C) 1997 Publis hed by Elsevier Science B.V.