VISIBLE AND INFRARED-SPECTRA OF MATRIX-ISOLATED PERYLENE CATIONS

Perylene radical cations have been produced via low-energy electron impact of a vapor phase mixture of perylene, argon and carbon tetrachloride. The cations have been trapped and stabilized in an argon matrix at 12 K in sufficient quantities to observe their infrared (and visible) absorption spectra. A strong green (534 nm) electronic absorption band, previously produced by gamma-irradiation of perylene in an s-butylchloride matrix (77 K), has been ascribed to the perylene cation. A positive correlation has been found between this band and the newly observed infrared bands at 1 128, 1318, 1346, 1349, and 1551 cm-1. The integrated intensities of these and other bands, assigned to the perylene cation, have been measured and are discussed in light of the recent suggestion that polycyclic aromatic hydrocarbons are the carriers of the unidentified infrared emission bands observed from interstellar space.