Selective identification of cyclopentaring-fused PAHs and side-substituted PAHs in a low pressure premixed sooting flame by photoelectron photoion coincidence spectroscopy

Abstract

This work reports on the selective on-line identification of polycyclic aromatic hydrocarbons (PAHs) formed in a low-pressure methane sooting flame, carried out using the double imaging Photoelectron Photoion Coincidence Spectroscopy method (i²PEPICO) on the DESIRS VUV beamline at the synchrotron SOLEIL. Generally, this work demonstrates the capabilities of the i²PEPICO method to identify PAHs in sooting flames, and in particular to distinguish cyclopentaring-fused PAHs (CP-PAHs) and side-substituted PAHs from their benzenoid isomers. Experimental threshold photoelectron spectra of four CP-PAHs: acenapthylene (C₁₂H₈, 152 m/z), acenaphtene (C₁₂H₁₀, 154 m/z), fluoranthene (C₁₆H₁₀, 202 m/z) and benzo(ghi)fluoranthene (C₁₈H₁₀, 226 m/z) are also reported for the first time.