Isomeric identification of polycyclic aromatic hydrocarbons formed in combustion with tunable vacuum ultraviolet photoionization

Abstract

Polycyclic aromatic hydrocarbons (PAHs) play important roles in the formation of soot from combustion. The PAHs are formed from incomplete combustion, and are thought to pose a particularly great risk to health. Isomeric identification of PAHs is a big challenge. In this article, we describe an apparatus that combines tunable synchrotron vacuum ultraviolet (VUV) photoionization with molecular-beam mass spectrometry for identifying isomers of PAHs formed in combustion. The isomers of PAHs can be distinguished with measurements of photoionization mass spectrometry and photoionization efficiency spectra. With its unique features, the apparatus provides superior mass and energy resolution and is potentially a powerful tool for the study of formation mechanisms of PAHs and soot in combustion.