Lo, Davy Y. and Tombrello, T. A. and Shapiro, M. H. (1989) Molecular dynamics simulation of preferential sputtering from isotopic mixtures. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 40-41 . pp. 270-274. ISSN 0168-583X. doi:10.1016/0168-583X(89)90976-2. https://resolver.caltech.edu/CaltechAUTHORS:20141031-091254877
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Abstract
The nonstoichiometric sputtering of different isotopes from elemental targets containing two and three isotopes is simulated with molecular dynamics. Cu targets consisting of isotopes with artificially high mass differences ranging from 10% to 30% are bombarded with normally incident 5 keV Ar^+ ions. Both liquid and single crystal targets are studied. Both backward and forward sputtering spectra are examined. Overall enrichments of the lighter isotopes in the sputtering material are observed in all cases with a consistent lower enrichment in the material sputtered forward for the liquid targets. Simulation results show a linear dependence of the isotopic fractionation (fractional change of the isotopic ratio in the sputtered atoms from the stoichiometric value) on the mass difference in the three-isotope system within statistical uncertainties. A clear dependence of the isotopic fractionation on the angle of emission with a larger enhancement of the lighter isotope in materials ejected toward the surface normal is observed for the crystal targets but not for liquid. For the liquid targets, a larger isotopic fractionation in the backward sputtering yield is seen. An ion mass dependence is also noted with a higher fractionation effect for the lighter ion.
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| Additional Information: | © 1989 Elsevier Science Publishers B.V. Supported in part by the US National Science Foundation (DMR86-15641). We wish to thank the NSF for providing computation time on the Cray-XMP at the San Diego Supercomputer Center. Many thanks also go to the physics department of California State University at Fullerton for free access to their computing facilities. Helpful suggestions through enjoyable conservations with Steve Spicklemire, Don E. Harrison, Jr., and Peter Sigmund are acknowledged. The writing of th.is article coincides with the passing away of Don E. Harrison, Jr., who has given invaluable guidance to the work of this group. Don will be deeply missed by everyone. | |||||||||
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| DOI: | 10.1016/0168-583X(89)90976-2 | |||||||||
| Record Number: | CaltechAUTHORS:20141031-091254877 | |||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20141031-091254877 | |||||||||
| Official Citation: | Davy Y. Lo, T.A. Tombrello, M.H. Shapiro, Molecular dynamics simulation of preferential sputtering from isotopic mixtures, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, Volumes 40–41, Part 1, 2 April 1989, Pages 270-274, ISSN 0168-583X, http://dx.doi.org/10.1016/0168-583X(89)90976-2. (http://www.sciencedirect.com/science/article/pii/0168583X89909762) | |||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | |||||||||
| ID Code: | 51105 | |||||||||
| Collection: | CaltechAUTHORS | |||||||||
| Deposited By: | Tony Diaz | |||||||||
| Deposited On: | 31 Oct 2014 16:18 | |||||||||
| Last Modified: | 10 Nov 2021 19:05 |
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