The effect of oxygen on the sputtering of metastable atoms and ions from Ba metal

By means of the Doppler-Shift-Laser-Fluorescence technique we have measured the effect of oxygen coverage on the velocity distributions and relative yields of sputtered Ba atoms and ions in both the ground and metastable excited states. Our measurements show no evidence that the excitation probabilities are correlated with the magnitude of the electric-dipole-moment matrix element to the ground state. We also find that the excitation probability of the Ba(1 D) state from a clean metal surface depends strongly on the emission velocity υ and approaches the functional form exp( -A av) at higher velocities. © 1983.