Ultrafast processes in Feɪɪɪ complexes with malic and succinic acids in aqueous solutions

Femtosecond pump–probe spectroscopy is used to reveal photophysical processes in Fe^ɪɪɪ complexes with two dicarboxylic acids (malic and succinic) in aqueous solutions. A model of primary photoprocesses is proposed that includes ultrafast vibrational cooling, solvent-mediated Franck–Condon excited-state relaxation and subsequent internal conversion to the ground state, accompanied by the formation of a long-lived Fe^ɪɪ radical complex.