Chapter 11 – Multivariate curve resolution of (ultra)fast photoinduced process spectroscopy data

Multivariate curve resolution-alternating least squares (MCR-ALS) is a widely used method to resolve multicomponent evolving chemical systems such as processes and reactions into pure contributions. This chapter presents the use of MCR-ALS to analyze time-resolved spectroscopy (TRS) data of molecular processes induced by light occurring in the second to femtosecond time domains. After a short introduction of the photochemical and photophysical processes and a presentation of the basics of TRS measurements, the chapter focuses on the application of MCR-ALS for the resolution of TRS data in order to obtain kinetic profiles and spectra of the species formed after light irradiation. Practical aspects covering data preprocessing, multiset analysis, or the implementation of kinetic constraints are presented. Three illustrative examples are discussed investigating the spectrodynamic of the photoinduced processes occurring at different timescales.