A new and highly sensitive &bgr;‐NMR method to study adsorbates on single‐crystal surfaces is presented. Contrary to conventional NMR, this method combines (via optical pumping) a high, nonthermal polarization of the adsorbed species with a particle counting method. Here, the &bgr;‐active isotope8Li is produced in the nuclear reaction D(7Li,8Li)H using a high‐pressure deuterium gas target. The fast8Li ions are subsequently implanted into a hot graphite block where they thermally diffuse to the surface and desorb. The desorbing thermal velocity8Li atoms are shaped into an atomic beam. Using a frequency modulated laser beam the atoms are transferred into a single hyperfine state by optical pumping. The so‐achieved nuclear polarization of the atoms (before impinging on the single‐crystal surface) is approximately 0.8 and can be switched in sign by an adiabatic high‐frequency transition. The atoms adsorb on the single‐crystal surface and their polarization—either freely decaying on the surface or driven by an external radio‐frequency field—is observed via the decay asymmetry of the nuclear &bgr;‐decay of the8Li nuclei. This method realizes an effective sensitivity to the active NMR isotope of 5×103atoms/cm2, which corresponds to a stationary coverage of 10−11of a monolayer. The typical electron count rate is 400 Hz during &bgr;‐NMR experiments. ©1995 American Institute of Physics.