On the multiplicity of field evaporation events in atom probe: A new dimension to the analysis of mass spectra

Author： Yao L.

ISSN： 1362-3036

Source： Philosophical Magazine Letters, Vol.90, Iss.2, 2010-02, pp. : 121-129

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Abstract

We introduce a filtering technique for atom probe microscopy data that is based on the multiplicity of detector events for each atom. We demonstrate that the resulting multi-dimensional mass spectra can be used to differentiate signal from noise and so the technique enhances the microscopic imaging and microanalysis capacity of atom probe in investigating the atomic-level dispersion of solutes in solid solutions. We have demonstrated this method in the analysis of C atoms in a low-alloy steel and found, somewhat unexpectedly, that the C atoms seem to participate in a surface migration prior to field evaporation. We propose that this is driven by electric field gradients. We also raise the possibility that, in some cases, the formation of complex ions prior to field evaporation may impact the detection efficiency.