The quantitative analysis of thin specimens: a review of progress from the Cliff‐Lorimer to the new ζ‐factor methods

Abstract

SummaryA new quantitative thin-film X-ray analysis procedure termed the ζ -factor method is proposed. This new ζ -factor method overcomes the two major limitations of the conventional CliffLorimer method for quantification: (1) use of pure-element rather than multielement, thin-specimen standards and (2) built-in X-ray absorption correction with simultaneous thickness determination. Combined with a universal, standard, thin specimen, a series of ζ -factors covering a significant fraction of the periodic table can be estimated. This ζ -factor estimation can also provide information about both the detector efficiency and the microscope-detector interface system. Light-element analysis can also be performed more easily because of the built-in absorption correction. Additionally, the new ζ -factor method has several advantages over the Cliff-Lorimer ratio method because information on the specimen thickness at the individual analysis points is produced simultaneously with compositions, thus permitting concurrent determination of the spatial resolution and the analytical sensitivity. In this work, details of the ζ -factor method and how it improves on the Cliff-Lorimer approach are demonstrated, along with several applications.

Determination of quantitative distributions of heavy-metal stain in biological specimens by annular dark-field STEM

“…This is because the M edges at energy losses in the range 2000-2500 eV are too weak to detect, and the N edges at energy losses in the range 20-60 eV are superimposed on a strong background arising from excitations of valence electrons in the organic matrix (Egerton, 1996). X-ray microanalysis is better suited than EELS for identifying and quantifying heavy elements in a light matrix (Williams and Carter, 1996;Watanabe and Williams, 2006), where the typical detection limits are of the order of 10 -4 atomic fraction for a single spectrum acquired in 100 s. However, acquisition times would be prohibitively large when attempting to record images containing 10 6 pixels from large specimen areas. (LeFurgey et al, 1992).…”

On the diffusion mechanisms of fine-scaleγ′ in an advanced Ni-based superalloy

“…High-angle annular dark field (HAADF) imaging was performed with a convergence semi-angle of 12.5 mrad and a HAADF inner angle of 30 mrad. The thickness of the extracted particles was approximated as the measured particle width allowing compositional analysis to be achieved via an absorption-corrected EDX spectroscopy approach described elsewhere [14][15][16].…”

“…Here we demonstrate that energy dispersive X-ray (EDX) spectroscopy within the scanning transmission electron microscope (STEM) can also be applied to measure changes in phase chemistry for the γ precipitates in sub γ -solvus heat treated RR1000. Quantification is achieved by employing γ phase extraction [18] and absorption-corrected EDX spectroscopy [14][15][16]. In this paper we have applied this approach to study the size dependent compositional variations of γ precipitates in a microstructure formed in a super γ -solvus heat treated commercial RR1000 Ni-based superalloy cooled using a moderate rate of 10 K/min.…”

Standardless EDS Composition Analysis using Quantitative Annular Dark-Field Imaging

“…Although the method makes for a simple way to extract quantitative information, accurately calibrating K factors can be difficult. Another method for compositional EDS analysis is using the ζ-factor approach where the characteristic X-ray intensities are related to the mass-thickness and composition [2]. For both quantitative methods, samples are tilted to minimize channeling conditions; however, orientation along a low-order zone axis, resulting in strong channeling, is required for atomic scale analysis.…”