Pyrolysis and Spectroscopy of Cyclic Aromatic Combustion Intermediates

<p>We have studied the pyrolysis of aromatic combustion intermediates using\&nbsp;<span style="line-height: 1.6em;">an array of detection techniques. The molecules investigated include cyclic\&nbsp;</span><span style="line-height: 1.6em;">aromatic molecules with hydrocarbon substituents (ethylbenzene, n-propylbenzene,\&nbsp;</span><span style="line-height: 1.6em;">isopropylbenzene, and styrene), oxygen-containing substituents\&nbsp;</span><span style="line-height: 1.6em;">(anisole and phenol), triply substituted systems (vanillin), resonance stabilized\&nbsp;</span><span style="line-height: 1.6em;">radicals (benzyl radical and tropyl radical) and phenyl radical. At the exit of a\&nbsp;</span><span style="line-height: 1.6em;">resistively heated micro-reactor (1 mm inner diameter, 3 cm long), the pyrolysis\&nbsp;</span><span style="line-height: 1.6em;">fragments are detected using photoionization mass spectrometry (PIMS), matrix\&nbsp;</span><span style="line-height: 1.6em;">isolation vibrational spectroscopy, microwave spectroscopy, tunable VUV\&nbsp;</span><span style="line-height: 1.6em;">synchrotron-based PIMS, and table-top VUV PIMS with photoelectron photoion\&nbsp;</span><span style="line-height: 1.6em;">coincidence spectroscopy (PEPICO). This array of detection methods allows for the\&nbsp;</span><span style="line-height: 1.6em;">identification of all possible fragments including metastables, radicals, and atoms.\&nbsp;</span><span style="line-height: 1.6em;">The findings allow for detailed mechanistic information regarding which pathways\&nbsp;</span><span style="line-height: 1.6em;">are active at different pyrolysis temperatures. The findings can also be used to help\&nbsp;</span><span style="line-height: 1.6em;">identify products and individual isomers that are formed during the gas-phase\&nbsp;</span><span style="line-height: 1.6em;">thermal decomposition of aromatic systems. By providing direct experimental\&nbsp;</span><span style="line-height: 1.6em;">pyrolysis data, models for fuel decomposition and soot formation can be improved\&nbsp;</span><span style="line-height: 1.6em;">to help understand current combustion systems and eventually aid in the design of\&nbsp;</span><span style="line-height: 1.6em;">superior fuel sources in the near future.</span></p>