Schematic of the experimental setup. Femtosecond transient absorption measurements were performed with different probes: In the case of kinetics at single wavelengths we used the emission of a second NOPA spanning 530-600 nm as probe. The spectral window of the photodiodes (PD1 and PD2) is then set by interferometric filters (IF) for 550 nm and 580 nm. In the case of transient absorption spectra we used a stepping monochromator with photomultiplier (PMT). A chopper blocks every other pump pulse so that the absorption signal is defined by S := - log (PpumpON / PpumpOFF) with the transmitted probe intensity P. In a 4-f-zero-disperion grating compressor (also known as femtosecond pulse shaping setup, where an optical Fourier transform gives access to the spectrum of a pulse [Weiner, A. M. (2000) Rev. Sci. Instr. 71, 1929-1960]), the red wing of the pump spectrum was cut at 530 nm, so as to prevent excess background when probing the triplet region around 550 nm.
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