IR spectroscopy of PAH in 6-15{mu}m band

Using density functional theory, this paper investigates the effect such five- and seven-membered fused ring defects have on the infrared spectra of ovalene (OV; C_32_H_14_), circumovalene (c-OV; C_66_H_20_), and circumcircumovalene (cc-OV; C_112_H_26_).

The defects make only small changes to the overall infrared (IR) spectra, both in the mid-IR and in the far-IR, of these species. In addition to small shifts in the positions of the bands between the PAHs with and without defects, the most common effect of the defects is to increase the number of bands. Except for an anion with the Stone-Wales defect, all of the species studied have the C-C stretching band at 6.3um or at longer wavelengths, the position in Classes B and C astronomical PAH spectra.