Coming soon to AZtecWave – Point Automation and WDS Mapping

18^th August 2022 | Author: Rosie Jones

Anticipation

Two weeks ago, I had the pleasure of attending the Microscopy and Microanalysis conference in Portland, USA. I spoke at the conference about the new functionality we are currently developing in the AZtec software, which will be released later this year. This is:

• A new style of Automation for collecting WDS and/or EDS data from individual points or lines of points
• WDS Mapping for investigating the spatial distribution of elements, particularly trace elements or those affected by peak overlaps in the EDS spectrum and therefore cannot be accurately mapped using EDS

Why WDS Automation?

Being able to automate WDS analysis is more desirable than EDS analysis automation, as analysis involving WDS is typically slower. This is because WDS measures X-rays of a single wavelength/energy at a time (i.e. serial measurement), whereas EDS can measure all X-ray energies simultaneously (i.e. parallel measurement). In addition, EDS has a higher solid angle compared to WDS. Therefore, the count rate is typically higher and counting times shorter. Our software team has been working hard on developing functionality to automatically collect WDS (and/or EDS) data from individual points (i.e. selected stage positions) and lines of points. This enables the user to define and save positions on the sample(s) that they wish to analyse and then run the data acquisition automatically. Although a user needs to invest some time setting up points, they can then just leave the system running for the rest of the day/overnight/over a weekend – facilitating effective use of time and the instrument. This is a way of working that is often used for EMPA analysis, and in fact, which I used myself when I was a PhD student.

Point Automation in Action

In the upcoming release of AZtec, there will be options to select individual stage positions. Alternatively, a line of points can be set up by selecting two points – a start and end stage position – and then defining either the number of points along the line or the spacing of the points. WDS and/or EDS acquisition can also be combined with the collection of an electron image before and/or after the analysis. This is an ideal way to check and confirm the position that was analysed. Below you can see the promotional video that we were playing on our booth in the exhibition hall at M&M, relating to the new style of Automation coming soon to AZtec.

Enhanced Compositional Mapping

I also gave a talk in one of the conference sessions on enhanced compositional mapping on the SEM through combined EDS-WDS mapping in AZtecWave (see the abstract here). 

I presented data to show how WDS mapping can be used to enhance compositional mapping performed by EDS. In most situations, compositional mapping using EDS is optimal as the count rate is higher, and therefore elemental mapping is quicker. However, there are instances where WDS mapping is required to provide a full and accurate picture, either when:

• Elements are present in trace concentrations and therefore are below the limit of detection for EDS - WDS has a detection limit of <100 ppm for many elements, whereas EDS is approximately 1000 ppm
• Elements are affected by peak overlaps that cannot be sufficiently resolved by EDS - the spectral resolution of WDS is ~10x better than EDS and therefore WDS can be used to fully resolve and map elements affected by peak overlaps

I illustrated this with an example investigating multiphase inclusions in a steel sample. Some of the phases in the inclusion contain Rare Earth Elements (REE) that have overlapping peaks in the EDS spectrum. I showed how the Wave spectrometer and AZtecWave were used to identify and map low concentrations of Pr and Gd that were not identified using EDS. A video of the presentation I gave can be found here.

This is the first M&M I have attended in person, and it was fantastic to be speaking face-to-face with customers, collaborators, and colleagues based in the Americas.

If you are interested to know more about WDS, AZtecWave, or the new functionality that is going to be coming to AZtec then please comment below, or feel free to contact me directly. I will also be presenting a webinar on WDS Mapping and Automation on the 27^th October – do look out for this!

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