Sputtering rates of minerals and implications for abundances of solar elements in lunar samples

A. J.T. Jull, G. C. Wilson, J. V.P. Long, S. J.B. Reed, C. T. Pillinger

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

Sputtering rates of minerals have been investigated using the ion microprobe and confirmed by interferometry. Relative erosion rates in an ion microprobe indicate a variation in mineral specific sputtering of a factor of about 9. Evidence from investigation of pit depths give values similar to those from the ion probe. It is possible to compare results to lunar surface sputtering rates by using the theory of Smith1 to convert from laboratory to lunar surface values. This calculation is, however, limited by the applicability of existing theory to complex silicate materials. We found apparent dose-dependent effects of sputtering rate as a function of primary beam intensity (30 keV O- primary beam). These effects could be important at the lunar surface, where, because of the long (105 y) exposure times, a very low incident flux of 2 × 108 atoms/cm2 s of H results in a very high total dose of 1020 atoms/cm2 H. Despite possible departures from linearity, calculations of saturation concentrations (assuming a sputter-equilibrium) for 36Ar and carbon indicate surface abundances of these elements of saturation grains are similar to experimental values. Heavier solar wind elements appear to be influenced by sputtering effects, high surface concentrations (1015/cm2) of Fe measured in plagioclases2) require a lower sputter rate than that calculated for plagioclase at the lunar surface. This may be a result of departure from theory due to dose dependent or other effects. If these can be quantified, and corrected for, variations in solar wind flux, energy and H/He ratio may be observable by looking for mineral grains with anomalously high or low concentrations of these elements.

Original languageEnglish (US)
Pages (from-to)357-365
Number of pages9
JournalNuclear Instruments and Methods
Volume168
Issue number1-3
DOIs
StatePublished - Jan 1 1980
Externally publishedYes

ASJC Scopus subject areas

  • Medicine(all)

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