INFRARED-SPECTROSCOPY OF MATRIX-ISOLATED POLYCYCLIC AROMATIC-HYDROCARBONS - 3 - FLUORANTHENE AND THE BENZOFLUORANTHENES

Matrix isolation techniques have been used to measure the 4000-500 cm( -1) infrared spectra of the polycyclic aromatic hydrocarbons (PAHs) fl uoranthene, benzo[a]fluoranthene, benzo[b]fluoranthene, benzo[j]fluora nthene, benzo[k]fluoranthene, and benzo[ghi]fluoranthene. For the PAHs where previous matrix isolation and gasphase laboratory studies are a vailable, agreements between the data sets are generally very good. Wh ile the fluoranthenes as a class produce infrared spectra that share m any of the same characteristics of the spectra of PAHs containing only benzenoid moieties, for comparably sized molecules, the fluoranthenes tend to produce more absorption bands overall and considerably more a nd stronger bands in the 1550-1350 cm(-1) range. These differences are largely due to the presence of the five-membered cyclopentadienyl rin g characteristic of the family.