Vibronic fine-structure in the S0 → S1 absorption spectrum of zinc porphyrin: A Franck-Condon simulation incorporating Herzberg-Teller theory and the Duschinsky effect

► The vibronic fine structure of S0 → S1 transition (the Q band) of zinc porphyrin was simulated theoretically. ► The FC and FCHT approximations were used to simulate the highly resolved spectra. ► The assignment and origin of the observed vibrational transitions in the Q band of zinc porphyrin were provided.