Femtosecond laser ablation inductively coupled plasma mass spectrometry: Fundamentals and capabilities for depth profiling analysis

“Laser ablation coupled to inductively coupled plasma mass spectrometry has become a versatile and powerful analytical method for direct solid analysis. The applicability has been demonstrated on a wide variety of samples, where major, minor, and trace element concentrations or isotope ratio determinations have been of interest. The pros and cons of UV-nsec laser ablation have been studied in detail, and indicate that aerosol generation, aerosol transport, and aerosol excitation–ionization within the ICP contribute to fractionation effects, which prevent this method from a more universal application to all matrices and all elements. Recent progresses in IR-fs and UV-fs laser ablation coupled to ICP-MS have been reported, which increase the inter-matrix and multi-element quantification capabilities of this method. These fundamental improvements in LA-ICP-MS are of significant importance for entering new applications in material science and related research fields. In particular, because coatings (conducting and non-conducting) consist of single or multilayers of various elemental composition and of different thickness (nm–mm range), significant progress in the field of depth profiling with fs-laser ablation can be expected. Therefore, in-depth profile analysis of polymers, semiconductors, and metal sample investigations, using ultra-fast laser ablation for sampling and the currently achievable figures of merit, are discussed. In this review manuscript, the enhanced capabilities of fs-LA-ICP-MS for direct solid sampling are highlighted, and it is discussed about current methods used for quantitative analysis and depth profiling, the ablation process of UV-ns and UV-fs, the influence of the laser beam profile, aerosol structure and transport efficiency, as well as the influence of the ICP-MS (e.g., vaporization and ionization efficiency in the plasma, and type of mass analyzer).”