H. Muller et al., ELECTRON-EMISSION IN LOW-ENERGY GRAZING COLLISIONS OF CO+ IONS WITH W(110) PARTIALLY COVERED BY CESIUM ATOMS, Chemical physics, 179(2), 1994, pp. 191-197
Electron energy spectra from slow CO+ ions (50 and 500 eV) colliding u
nder grazing incidence with W(110) surfaces are reported. The surface
work function was varied by the exposure to cesium atoms. The electron
energy spectra are interpreted in terms of various inter- and intra-a
tomic Auger processes: for clean W (110) and up to a Cs coverage of 0.
2 ML (in terms of one completed adlayer at room temperature) an unique
identification of the electronic transition processes could not be ma
de on the basis of the electron spectra. Some observations indicate ho
wever that, besides direct Auger capture into the CO ground state, als
o Auger deexcitation of excited CO molecules (a 3PI) to the CO ground
state and autodetachment of the CO- X2 PI shape resonance contribute t
o the spectra. With increasing Cs coverage excited states up to c 3PI
become populated manifesting themselves by a variety of Auger deexcita
tion processes. For Cs coverages larger than 0.6 monolayers the resona
nt capture of an electron from the surface by CO b,B 3,1SIGMA+ leads t
o the formation of the Feshbach resonance CO- B 2SIGMA+. Again the fo
rmation of the resonance is detected by its decay via autodetachment.