[Fine structure luminescence of etio-, copro- and mesoporphyrin following selective laser excitation]

Fluorescence line spectra of etio- and coproporphyrin isomers and mesoporphyrin IX, as well as their ionic forms have been obtained and investigated using a tunable dye laser excitation (T = 4.2 K). Normal vibrational frequencies in the ground electronic state of both the neutral molecules and their ions have been determined. By comparing the line spectra of different porphyrins and their isomers the distinctions have been revealed which may be used for the identification of these compounds in solutions. Changes have been discovered in the coproporphyrin ion spectra in different solvents.