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) b y Kef ISS and other methods, as well as a study of the He+ neutralisation r ate. 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 r emains very weak until about 1.5 L, when the CI to Ag ISS peak ratio increa ses strongly. Measurements of He+ neutralisation indicate an increase in ne utralisation in the initial stages of adsorption, and then a decrease at ex posures above 1.5 L, which we relate to AgCl island formation. The enhanced neutralisation in the submonolayer chemisorption range explains the low IS S signal corresponding to Cl. We associate the increase to a lower neutrali sation on AgCl. The efficiency of Cl detection is thus environment dependen t. (C) 2000 Published by Elsevier Science B.V. All rights reserved.