DEEXCITATION OF RARE-GAS METASTABLE ATOMS ON SEMICONDUCTOR SURFACES - MOS2 AND LACOO3

The metastable atom electron spectra (MAES) obtained by thermal collisions between He*(1s2s) atoms and semiconductor MoS2 and LaCoO3 surfaces were compared to the corresponding He I ultraviolet photoemission spectra. The metastable atoms are deexcited on the MoS2 surface predominantly via resonance ionization followed by Auger neutralization and on the LaCoO3 surface via Penning ionization. The deexcitation channel and the relative band intensity of the MAES are found to depend strongly on the spatial distributions of the occupied and unoccupied wavefunctions at the outermost surface layer.