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Published September 2015 | Supplemental Material
Journal Article Open

Ion Implants as Matrix-Appropriate Calibrators for Geochemical Ion Probe Analyses

Abstract

Ion microprobe elemental and isotopic determinations can be precise but difficult to quantify. Error is introduced when the reference material and the sample to be analysed have different compositions. Mitigation of such "matrix effects" is possible using ion implants. If a compositionally homogeneous reference material is available which is "matrix-appropriate," i.e., close in major element composition to the sample to be analysed, but having an unknown concentration of the element, E, to be determined, ion implantation can be used to introduce a known amount of an E isotope, calibrating the E concentration and producing a matrix-appropriate calibrator. Nominal implant fluences (ions cm^(−2)) are inaccurate by amounts up to approximately 30%. However, ion implantation gives uniform fluences over large areas, thus it is possible to "co-implant" an additional reference material of any bulk composition having known amounts of E, independently calibrating the implant fluence. Isotope-ratio measurement standards can be produced by implanting two different isotopes, but permil level precision requires post-implant calibration of the implant isotopic ratio. Examples discussed include: (1) standardising Li in melilite; (2) calibrating a ^(25)Mg implant fluence using NIST SRM 617 glass; and (3) using Si co-implanted with ^(25)Mg alongside NIST SRM 617 to produce a calibrated measurement of Mg in Si.

Additional Information

© 2014 The Authors. Geostandards and Geoanalytical Research © 2014 International Association of Geoanalysts. Received 15 Apr 14; Accepted 09 Sep 14. Article first published online: 29 Jan 2015. The authors thank two anonymous reviewers and the editors for helpful comments on the manuscript. Support for this work is greatly acknowledged from NASA LARS grants NNX14AF26G (Burnett), NNX13AD13G (McKeegan), NNX07AG19G (Nittler), NNX09AC62G (Humayun) and NNX13AD11G (Humayun); NASA Cosmochemistry grant NNX10AJ15G (Paque) and NSF EAR-0948878 (Hervig).

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Supplemental Material - ggr12054-sup-0001-AppendixS1.pdf

Supplemental Material - ggr12054-sup-0002-AppendixS2.pdf

Supplemental Material - ggr12054-sup-0003-AppendixS3.pdf

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Additional details

Created:
August 22, 2023
Modified:
October 18, 2023