On low energy ion scattering spectroscopy and chlorine adsorption on silver

We present the results of a comparative study of Cl adsorption on Ag(lll) by Kef ISS and other methods, as well as a study of the He+ neutralisation rate. Workfunction and time of flight spectroscopy measurements show that Cl adsorption occurs rapidly in the 0-1.2 L range, and thereafter saturates. He+ ISS illustrates the appearance of Cl at low exposures, but the signal remains very weak until about 1.5 L, when the CI to Ag ISS peak ratio increases strongly. Measurements of He+ neutralisation indicate an increase in neutralisation in the initial stages of adsorption, and then a decrease at exposures above 1.5 L, which we relate to AgCl island formation. The enhanced neutralisation in the submonolayer chemisorption range explains the low ISS signal corresponding to Cl. We associate the increase to a lower neutralisation on AgCl. The efficiency of Cl detection is thus environment dependent. (C) 2000 Published by Elsevier Science B.V. All rights reserved.