High-Temperature Hydrocarbon Clustering and Particle Inception

HOPE MICHELSEN, James Rundel, Ray Bambha, Judit Zádor, K. Olof Johansson, Paul Schrader, Kevin R. Wilson, University of Colorado, Boulder

     Abstract Number: 413
     Working Group: Combustion

Abstract
Soot is formed during the incomplete combustion and pyrolysis of hydrocarbon fuels and has an enormous impact on human health and the environment. It is responsible for a majority of the more than 7 million premature deaths attributed to air pollution worldwide annually, and it is the second leading cause of global warming. Despite its ubiquity, the chemical pathways leading to its formation are shrouded in mystery. We hypothesize that radical chain reactions driven by resonance-stabilized hydrocarbon radicals are responsible for particle inception. We have performed targeted experiments to explore and test this hypothesis. Vacuum-ultraviolet aerosol mass spectrometry (VUV-AMS) has provided a wealth of information about the species involved in particle inception. VUV-AMS measurements of particles formed during pyrolysis have demonstrated that temperatures at which particles are influenced by the availability of resonance-stabilized radicals. In this talk, we present evidence for clustering of hydrocarbons driven by reactions initiated by such radicals.