Knowledge Bank

The low energy electron impact Technique has been employed to ionize tetracene and pentacene in an Ar or Ar/0.1% $CCl4$ gas phase mixture. The electron bombardment products were deposited and stabilized in an argon matrix at 12K. An intensity correlation between the 392mm (tetracene) or 954mm (pentacene) electronic bands due to the radical cations and the newly observed vibrational bands was sought by varying the ratio of the abundance of tetracene or pentacene cations to all other species in the matrix. For these, and other polycyclic aromatic; hydrocarbons reported $earlier1$, the intensity distribution of the IR bands is significantly different from the intensity distribution of the neutral parents. The analysis of the vibrational energy shifts versus local charge density values for some normal modes for the series of linear polycyclic aromatic hydrocarbon cations from naphthalene to pentacene will be presented.