Dr. Shangshang Mu, Applications Engineer, Gatan/EDAX
Cipher®, the quantitative analysis of lithium system, is a shining example of the synergies brought about by the merger between Gatan and EDAX. As an application specialist involved since the beginning of this project, witnessing the evolution of the data acquisition and analysis workflow is nothing short of astounding. I vividly recall those initial moments when we tested this concept and generated our first Li measurements from an actual sample.
I conducted energy dispersive x-ray spectroscopy (EDS) data acquisition and analysis in the EDAX APEX™ software during those early stages. At the same time, my colleague focused on the quantitative backscattered electron (qBSE) work within the DigitalMicrograph® software. To analyze the lithium content in a sample from just a few locations was a painstaking process requiring the laborious process of correlating information from disparate software programs manually, checking again and again that the same area of the sample was being analyzed, and then calculating by hand the lithium content of an analysis location using a variety of different mathematical models to determine the best one.
With the release of DigitalMicrograph 3.6.0, the entire data acquisition and analysis workflow unfolds seamlessly, marking a significant advancement in efficiency and user-friendliness, not to mention making my job so much easier! A guided workflow allows a user to conduct the whole experiment using a single software package. Using the Technique Manager, data acquisition and analysis happen step-by-step as you progress from the top palette to the bottom (Figure 1).
Several steps used to be challenging experimentally, which the software now manages for you, including:
- Ensuring that the backscattered electron signal was calibrated by atomic number (Z) and, importantly, that there were no changes to the calibration when moving between samples
- That data that was captured sequentially could be aligned and transformed before the lithium content being calculated
- Use of the latest models for qBSE and EDS analysis methods
For the first challenge, appropriate Z-standards are required, and the detector settings and collection geometry must remain constant between qBSE measurements. The qBSE Calibration palette (Figure 2) provides intuitive guidance through this essential process, and when using the Z-standards provided with the system, what used to take an hour or more to complete can now be done in minutes. The buttons of the qBSE calibration palette guide you through the detector setup and measurement of the Z reference samples, populating the calibration table as you go. A calibration curve can be plotted for your reference once a minimum of four reference values are acquired. Vitally, the software continuously verifies that you are at the correct working distance for qBSE. If a measurement is attempted using incorrect conditions, qBSE data cannot be generated. Furthermore, the QuickSet button becomes active, allowing the user to launch a wizard that returns the system to the appropriate conditions for qBSE analysis. This has proven invaluable for many of the customer specimens I have analyzed, as they come in all shapes and sizes!
For samples analyzed in the SEM, DigitalMicrograph 3.6 now uses the same standardless EDAX eZAF method for analysis as APEX EDS Advanced software, enabling quantified EDS measurements to be performed reliably in the same software program as used for qBSE data collection. However, to ensure that the analyzed volume is consistent between the two methods, we typically collect data for the two signals at different accelerating voltages. Previously (e.g., [1]), the complexity of registering and aligning the qBSE and EDS data was too challenging to even attempt to map the lithium distribution, with researchers instead choosing to analyze a few isolated points only.
The Cipher Analysis palette (Figure 3) simplifies the process of correlating EDS and qBSE datasets like never before, enabling lithium content to be mapped over a 2D area or 1D line scan in addition to point analyses. By simply selecting the BSE and EDS workspaces from the dropdowns and clicking on the Align button, qBSE and EDS data captured under different conditions will be automatically registered and aligned using the corresponding secondary electron images; this alignment procedure even works if the qBSE and EDS data is captured at different magnifications or pixel density.
Subsequently, pressing Map Low Z will generate Li maps effortlessly using the latest algorithms in EDS and qBSE analysis (Figure 4), adjusting the original elemental maps to include the Li content.
Looking ahead, the streamlined workflow in DigitalMicrograph and the continued evolution of Cipher promises to revolutionize lithium analysis, empowering researchers with unprecedented insights into battery technology, energy storage, and many other fields. I’m excited to be able to be involved with the development and release of a product that turns what was once impossible into a straightforward experiment.