Electronic transition energies have been predicted for cations of dehydrogenated coronene, C 24 H , based on laboratory data for hydrogenated molecules. This has resulted in the tentative simulation of many of the diffuse interstellar bands, including the majority of the strongest bands. It is shown that many of the diffuse bands can be identified with π ← π -2,-3 , π ← π -4,-5 , and π ← π -6,-7 transitions of C 24 H , where x {12, 10, 8, 6, 4, 2, 0}. A π ← π transition in the fully dehydrogenated cation, C , occurs at 442.8 nm. Diffuse interstellar band spectra reveal a well-defined spectral sequence between 653.2 and 628.4 nm correlating with the small change in ionization potential that accompanies the sequential removal of H atoms from coronene. As previously suggested by mass spectra, only cations with an even number of H atoms are observed. All bands associated with these ions show vibronic structure, with vibrational frequencies that correspond to those observed in aromatic infrared emission sources. This establishes that the molecules responsible for the diffuse interstellar bands are also likely the source of the aromatic emission bands.
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W. W. Duley (2006) studied this question.
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