ADATOM YIELDS, SPUTTERING YIELDS, AND DAMAGE PATTERNS OF SINGLE-ION IMPACTS ON PT(111)

Scanning-tunneling-microscopy methods are presented, which allow us to determine the adatom yield, the number of adatoms created per primary ion, and the sputtering yield. The reliability and the possible errors of the scanning-tunneling-microscope yield-determination methods are analyzed. For noble-gas ions normally incident on Pt(111), the dependence of adatom and sputtering yields on ion energy and ion mass are determined. The dependence of the adatom yield on these quantities is not in agreement with previous theoretical predictions. Possible mechanisms for the observed ion-energy and ion-mass dependence of. the adatom yield are suggested. The observation of the damage patterns of single keV ion impacts and the lateral distribution of the damage features gives additional information on the damage mechanism.