SIMULATION OF THE ISOTOPIC ANGULAR PATTERN DURING THE MO-92-MO-100 SPUTTERING

In the sputtering of a Mo-92-Mo-100 target induced by 5 keV Ar ions, b oth static and dynamic Monte Carlo simulation programs have been used to estimate both the angular variations in isotopic enrichment from ze ro to high fluences, and the momentum flux ratios as a function of sur face depth at the zero fluence. The calculations show that the isotopi c ratio in the near-normal direction is positive and quite large at th e zero fluence, then it decreases with increasing fluence. The calcula tions also show that the difference between the near-normal isotopic r atio and the oblique isotopic ratio is large and positive at both the zero and the high fluences, then this difference minimizes at a low fl uence between the two fluence limits. The calculations indicate that d epth-dependent momentum asymmetry significantly exists in the near-sur face region.