Carbon fibre reinforced materials are becoming increasingly more prevalent across a wide range of industries. Due to the high value of carbon fibres in various fields, their production conditions, treatments, and finishing are typically closely guarded and so fundamental understanding of carbon fibre structure is imperative to future applications. Atom probe tomography (APT) is uniquely placed to address this situation because it provides a combination of highly resolved chemical and spatial information in three dimensions with the ability to detect all the elements (and their isotopes) in the periodic table. APT is thus a very suitable technique for analysis of carbon fibres, which are mostly comprised of light elements (namely C, H, N, and O) that are otherwise very challenging to detect in combination with each other using other microscopy and microanalysis techniques, pushing the limits of detection with respect to spatial resolution, chemical sensitivity and mass resolving power.
There are, however, significant challenges for accurate and unambiguous APT mass spectral analysis given the rate of incidence of detection of carbon molecular ions and complex molecular ionic species. Furthermore, the potentials used in the APT technique are typically at the kV level, which is more than adequate to cause substantial fragmentation of the molecular species of which this material is composed. Analysis of the correlation of field evaporated ions [1] also reveals frequent instances of molecular ion dissociation. While field-induced molecular fragmentation may be viewed as a drawback, analysis of these products facilitates a basis for comparison of key fragments (such as C=O) between different fibres or fibre treatments, and also for comparison of this type of APT data with that from other characterisation techniques typically used to investigate carbon fibre, such as X-ray photoelectron spectroscopy (XPS) [2,3] and time-of-flight secondary ion mass spectroscopy (TOF-SIMS) [3,4].