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Trace element analyses on SHRIMP-RG

In practice, any solid material can be measured on SHRIMP-RG for trace element or isotopic composition. The practicle limitations for obtaining quantitative compositional data are (1) standardization, (2) the abundance of the element(s) of interest, (3) possible isobaric interferences at the mass of interest, and (4) the precision required to answer your research questions. Because SIMS is a relative measurement approach, quantitative analyses require a matrix-matched standards that has been previously characterized for age, trace element and/or isotopic composition. The samples must also be mounted with a flat, polished surface.

If would like to propose new measurements on minerals that are not routinely measured (see above), we will need to work together to find appropriate standards. The high-mass resolution of the SHRIMP-RG allows measurements to be performed in-situ on polished rock samples (rock chips or thin sections) or mounted mineral separates (e.g., epoxy or indium mounted minerals) without the need for chemical separation or purification. Also, the high-sensitivitity of the SHRIMP-RG permits trace elements to me measured at ppb-level concentrations.

Most elements that are present at the ppm-level can be analyzed on SHRIMP-RG, but several exceptions occur. The figues below show relative ionization efficiency for elements using the O- vs Cs+ primary ion beams. At Stanford, we most typically use a O2- primary ion beam to measure possitive seconday ions.