2015 Cameca Users Meeting KαKα K L M Fluorescence and absorption… A sample of olivine has Fe, Mg and Si. Fe K α = 6.4 keV Binding energies… Mg K = 1.30 keV Si K = 1.84 keV Fe Kα excites both Si Kα and Mg Kα, resulting in “too much” intensity for Mg and Si, meanwhile, the Fe Kα intensity decreases due to absorption by Si and Mg, resulting in “too little” intensity of Fe… However, Fe LIII edge (binding energy) = 707 eV reduces Mg Kα and Si Kα intensities, so competing factors!

2015 Cameca Users Meeting Fe-Ca silicate Fe-Ca sil. Ca Kα Fluorescence at a distance… Fe silicate High energy Fe Kα fluoresces Ca Kα in adjacent phase. Analysis “sees” Ca at this beam position.

2015 Cameca Users Meeting Fluorescence range

The difficult problem of boundary fluorescence… Electrons may not go far, but X-rays do 2015 Cameca Users Meeting

The difficult problem of boundary fluorescence… More blank testing… Line or grid acquisition: Most analyses will be wrong! 20 μm Th Mα 6.31+/ / / Monazite Th concentration 2015 Cameca Users Meeting

Penepma Francesc Salvat and Xavier Llovet

2015 Cameca Users Meeting Mid 1990s = code system PENELOPE 2000s = EPMA related main program PENEPMA Simulates X-ray emission spectra Computationally very lengthy, so not suitable for real-time data processing

2015 Cameca Users Meeting Fast calculation - semi-analytical method developed Use physical interaction parameters from PENELOPE numerical database Use primary photon intensities obtained by short MC simulation runs to create parameter files for each material in a boundary couple X-ray intensity with distance is modelled, which permits the estimation of k-ratios and calculated concentrations resulting from fluorescence.

2015 Cameca Users Meeting

Petrology of Chromite in Ureilites: Implications for Primary Petrogenesis and Secondary Processes –C.A. Goodrich et al

2015 Cameca Users Meeting rutile Ti K edge =4.96 keV La Lβ =5.04 keV monazite

2015 Cameca Users Meeting rutile

2015 Cameca Users Meeting

Rutile inclusions

2015 Cameca Users Meeting