Correction for the time dependent inner filter effect caused by transient absorption in femtosecond stimulated Raman experiment

Femtosecond stimulated Raman spectroscopy (FSRS) is a promising multiple-pulse ultrafast spectroscopic tool whose simplest form utilizes an actinic pump, a Raman pump and a continuum probe. Here, we report that the transient absorption generated by the actinic pulse modulates the overall magnitude of the Raman signals of the photoactivated sample. As a consequence, the traditional transient FSRS signal is distorted by artifacts, which were observed in the past but left without interpretation. We propose a simple model to calculate the correct transient FSRS signals from the knowledge of transient absorption signal. The model was verified by application to experimental data.