CHARGE-EXCHANGE IN LOW-ENERGY D+ SCATTERING FROM MO(111)

Energy spectra of deuterium positive ions backscattered from clean and oxygen-saturated Mo(111) surfaces are reported with use of D+ and neutral D0 beams with energies below 1 keV. The D+ spectrum from the clean Mo(111) surface shows a clear peak corresponding to Mo with very low background intensity. The spectral peak is far smaller in intensity than that for He+ scattering and exhibits characteristics of surface scattering of D+ ions surviving neutralization on their incoming and outgoing trajectories. The background increases with increase of the oxygen exposure and is caused by reionization of neutral D0 scattered after significant penetration into the solid, which is confirmed on the basis of the experiments on ionization of the incident D0 beam.