Infrared Spectroscopy of Matrix-Isolated Neutral and Ionized Anthracoronene in Argon.

The matrix-isolated mid-IR (MIR) spectrum of neutral and ionized anthracoronene (C36H18, AnthCor) in argon has been measured experimentally, compared to the spectrum of its parent molecules, coronene and anthracene, and analyzed by comparison to a theoretical spectrum computed using density functional theory (DFT). The experimental and theoretical band positions generally agree within 0-10 cm-1. Anthracoronene exhibits extremely intense cation and anion bands around 1330 and 1318 cm-1. The intensity of these two bands approaches what is traditionally observed over the entire 1000-1600 cm-1 range for a typical PAH cation or anion. The matrix-isolated near-IR (NIR) through overlap region (OVR) spectrum of ionized AnthCor in argon has been reported for the first time and compared to the spectrum of its parent molecules, coronene and anthracene. The spectrum of AnthCor contains a very strong electronic transition around 6175 cm-1, placing it outside the range of the electronic transitions typically observed for PAHs. Anthracoronene is one of the few PAHs studied to date which has exhibited the formation of anions upon UV photolysis.