Hybrid hard- and soft-modeling approach for the resolution of convoluted femtosecond spectrokinetic data

This work tackles the problem of convolution of femtosecond spectrokinetic data with the instantaneous response function (IRF) of the measurement by hybrid hard- and soft-modeling multivariate curve resolution (MCR). Fitting the time-dependent concentration profiles obtained during the MCR iterative optimization by a kinetic model convoluted with a parametric description of the IRF, the approach benefits of the advantages of both hard- and soft-modeling. The performance of the method is first proven on synthetic data sets with overlap of pure time-dependent concentration and/or spectral profiles and presence of interfering contributions. The method is afterwards applied to the resolution of femtosecond transient absorption spectroscopy data probing ultrafast photoinduced processes implied in the photochromism of anils. An excited-state proton transfer appearing in ~ 80 fs is characterized using an instrumental system with a severe influence of the convoluted instrumental response function, defined by a time resolution of ~ 150 fs.