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Chapitre D'ouvrage Année : 2015

Chemometrics of ultrafast time-resolved spectroscopy data

Résumé

In this day and age, optical spectral data can be acquired with a time resolution in the picosecond–femtosecond time domain using pump-probe experimental set-ups. For time-resolved spectroscopy, as in other fields among analytical chemistry, data analysis plays an integral part of the measurement. Chemometrics has been neglected in time-resolved spectroscopy for a number of reasons. Methods based on parametric models, such as global data analysis based on a weighted sum of exponential decays, which is hypothesized even before data are acquired, have been preferred.

The situation has changed in the past few years witnessing the application of ultrafast spectroscopic techniques to investigate the spectro-dynamic properties of complex photochemical or photobiological systems. Unraveling these processes can only be achieved considering data-driven and exploratory approaches dedicated to extracting relevant aspects from the measurement of empirical phenomena. In this article, we intend to focus on a chemometric approach to the analysis of time-resolved spectroscopy data. We aim to provide readers who are not specialized in the topics with the critical information required to understand and perform the basic steps.

A chemometric analysis might involve different steps. Each step provides new information about the data and increases knowledge of the investigated system. Interpretation of the results should help answering the ‘chemical’ issue investigated. Data preprocessing of some kind is usually the first action taken followed by exploratory data investigation, which may involve data representation. The next step is soft-modeling, which provides data description derived from a structural model of the data. This structure corresponds to a general and chemically informed idea about the data, such as Beer-Lambert law for absorption spectroscopy. From the information provided by soft-modeling, the analyst can start answering questions about the unknown process. These questions might concern the number of chemical species involved, the characteristic spectral features of the intermediates, and the reaction mechanism leading to the product. This may lead to the postulation of a reasonable kinetic model which validity can be checked.

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Dates et versions

hal-01206864 , version 1 (29-09-2015)

Identifiants

Citer

C. Ruckebusch, O. Devos, S. Aloïse, M. Sliwa. Chemometrics of ultrafast time-resolved spectroscopy data. Encyclopedia of Analytical Chemistry, 2015, 9780470027318. ⟨10.1002/9780470027318.a9437⟩. ⟨hal-01206864⟩
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