Photofragmentation spectrum of protonated phenanthridine compared to the simulated spectrum: a) the experimental spectrum plotted as the fragment ion signal (arbitrary units) as a function of the excitation energy; b) the simulated spectrum plotted as the Franck-Condon factors as a function of the excitation energy, calculated using the calculated ground and excited state frequencies. The main vibrational progressions (indicated in red in panel a)) ν₅ and ν₁₇, are illustrated schematically below the simulated spectrum.