Blog, Tutorials & Release Notes

Part 1 explains the concept of models and samples, introduces the main window, and demonstrates the interactive what-you-see-is-what-you-get model editor.

PEAXACT is an interactive Windows App for the quantitative analysis of UV/VIS/IR/Raman/NMR spectra. Its central element is a model. You create, edit, and train models, and then apply models to analyze measured samples. A PEAXACT model contains six sub-models:

• Data Pretreatment Model – provides options for the manipulation of sample spectra
• Integration Model – specifies peaks for peak integration
• Hard Model – a peak-based representation of spectra used by Spectral Hard Modeling methods (e.g., Indirect Hard Modeling and Hard Modeling Factor Analysis)
• Calibration Model – predicts numerical sample feature, e.g., concentrations
• Classification Model – identifies categorical sample features, e.g., for material class
• Custom Model – extends the built-in analyses by user-defined custom results

Use the PEAXACT main window to manage your models, create and edit new models, and conduct analyses to extract information from your spectra.

• The Models Panel (top-left) displays models as trees. Use it to navigate through the model tree.
• The Samples Panel (bottom-left) displays a list of loaded samples.
• The Properties Panel (top-right) displays model parameters and allows you to edit them.
• The Plot Panel (bottom-right) displays the selected model and spectrum. It offers a way to interactively edit the model with the cursor.

A nice concept of PEAXACT is its What-You-See-Is-What-You-Get (WYSIWYG) editor. For instance, if you make changes to the Pretreatment Model, you immediately see the effect on the selected spectrum. And if you drag an Integration Model Peak with the cursor, you immediately see how the peak area gets recalculated. You will learn more about Integration Models in Part 4 of this tour.

You can even interactively build and modify peak models – so-called Hard Models – to deconvolve complex overlapping signals. You will learn more about Hard Models in Part 5 of this tour.

Many of the modeling steps are also automated. But already visually examining how a model fits your spectra is a great way to learn more about the measured system. This makes modeling with PEAXACT a pleasant experience.

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