Infrared Cavity Ringdown Spectroscopy of Jet-Cooled Polycycllc Aromatic Hydrocarbons

摘要

Infared absorption spectra of the CH stretching region were observed for naphthalene, anthracene, phenanthrene, pyrene, and perylene using a heated, supersonic, slit-jet source and cavity ringdown spectroscopy. Band positions and intensities recorded with 0.2-cm~(-1) resolution were compared withprevious gas-phase and argon matrix isolation experiments, as well as theoretical caclulations. The largest matrix shift in the absorption maximum (-7.4 cm~(-1)) was observed for anthracene, with all others shifted by 3.0cm~(-1) or less. Spectral features in the supersonic jet spectrum were generally narrower than those observed in the Ar matrix, with the largest matrix broadening found for the peryiene (80% increase), low number densities observed for the larger polycydic aromatic hydrocarbons (PAHs)suggest that the lower vapor pressure of PAHs with catacondensed four-merhbered rings and with five-mempered rings other than peryiene will not be detectablei. using'Ourcurrent configuration.