Atom Probe Tomography
Atom probe tomography is a technique that rip minerals apart one atom at a time in order to digitally reconstruct them in 3-D. This powerful technique allows us to understand a wide array of fundamental mineralogical processes, which we can then
Complex mass spectra
Atom probe tomography was designed for relatively simple compounds. The default software was never designed for the elementally complex minerals that geoscientists look at. While I was a postdoc in the Research Group in Atom Probe Tomography and Reconstruction (RaPToR) at the University of Oxford I was involved in developing and refining a novel deconvolution technique to better deal with the complicated isobaric interferences found in geomaterials.
The code is primarily written by Andrew London and is freely available at:
APT to elucidate substitution mechanisms of trace elements
The mechanisms by which trace elements can incorporate into minerals can be theorized and modeled, but there has never been a way to directly determine substitution mechanisms for trace elements. We have therefore developed a new method using the statistics within the APT data to determine how trace elements substitute into minerals.
For more details see:
Gopon et al., 2019
The code for the stastical analysis was developed by Daniel Haley, and can be found here:
Nano-isotopes
While a postdoc at Oxford we tried an initial attempt at stable isotopic analysis, and ran into a fair few problems. After almost 4 years of hard work we know understand the physics and analytical issues of Atom Probe Tomography of Geomaterials well enough to be to have uncertainties approaching what is needed to solve the complex geochemical and ore deposit genesis question that we have. This work is summarized in our 2022 paper on stable isotopic analysis with the atom probe.
Our method allows us to measure stable isotopes (especially S isotopes in sulfide minerals) analysis at the nanoscale, using APT data. We have already used our method to show that nanoscale growth zones in sulfide minerals appear to show such large fractionations, that can best (only?) be described by rapid and repeated changed in fluid source for these deposits. We are currently working on applying our method to other minerals and isotopic systems, to unlock a range of geochemical processed in unprecedented detail.
The peak fitting code we used was written by Fred Meisenkothen and is freely available to use at:
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