USE OF SPIN-LABELING TECHNIQUES TO PROBE THE DYNAMICS OF HE(2 S-3) DEEXCITATION AT SOLID-SURFACES

Spin labelling techniques, specifically the use of electron-spin-polar ized He(2 S-3) metastable atoms coupled with energy-resolved spin anal ysis of the ejected electrons, are used to investigate the dynamics of He(2 3S) deexcitation at solid surfaces. Data for a clean Au(100) sur face are presented that show that deexcitation occurs exclusively thro ugh resonance ionization followed by Auger neutralization. The electro ns involved in Auger neutralization are observed to be correlated in s pin and possible reasons for this are discussed. Results obtained at X e and NO films adsorbed on cooled Au(100) and Cu(100) substrates, resp ectively, show that He(2 3S) metastable atom deexcitation is analogous to gas-phase Penning ionization. Detailed differences are apparent th at can be attributed to effects associated with the underlying substra te and interactions involving neighboring atoms in the film.