VIBRATIONAL AND ELECTRONIC-SPECTRA OF MATRIX-ISOLATED TETRACENE CATIONS

The electronic and vibrational spectra of tetracene cations, generated by vapor-phase electron bombardment and deposited in an argon matrix, have been recorded. Integrated intensities of the infrared bands of n eutral and cationic tetracene compare well with a recent density funct ional calculation by Langhoff, As observed in previous studies of PAH ions, the intense neutral out-of-plane CH bends decrease drastically i n the cation, while the very weak neutral in-plane CC stretches and CH bends gain dramatically upon ionization. The possible contribution of tetracene cations and neutrals to the 'unidentified interstellar infr ared' bands is discussed.