Paramagnetic centers in particulate formed from the oxidative pyrolysis of 1-methylnaphthalene in the presence of Fe(Ⅲ)_2O_3 nanoparticles

摘要

The identity of radical species associated with particulate formed from the oxidative pyrolysis of 1 -meth-ylnaphthalene (1-MN) was investigated using low temperature matrix isolation electron paramagnetic resonance spectroscopy (LTMI-EPR), a specialized technique that provided a method of sampling and analysis of the gas-phase paramagnetic components. A superimposed EPR signal was identified to be a mixture of organic radicals (carbon and oxygen-centered) and soot. The carbon-centered radicals were identified as a mixture of the resonance-stabilized indenyl, cyclopentadienyl, and naphthalene 1-meth-ylene radicals through the theoretical simulation of the radical's hyperfine structure. Formation of these radical species was promoted by the addition of Fe(Ⅲ)_2O_3 nanoparticles. Enhanced formation of resonance stabilized radicals from the addition of Fe(Ⅲ)_2O_3 nanoparticles can account for the observed increased sooting tendency associated with Fe(Ⅲ)_2O_3 nanoparticle addition.