| Abstract
| - The formation and temperature dependence of the total yields of radicals from the gas-phase pyrolysis of hydroquinone (HQ) over a temperature range of 350−950 °C was studied using the technique of low-temperature matrix isolation electron paramagnetic resonance (LTMI−EPR) spectroscopy. Annihilation procedures along with microwave power saturation studies of the frozen radicals as well as GC−MS analysis of products helped to clearly identify several types of radicals over the temperature range studied. On the basis of these results, three formation temperature regimes could be identified: low-temperature region from 350 to 725 °C, where neutral p-semiquinone (p-SQ) radical is dominant, high-temperature region from 850 to 975 °C, where cyclopentadienyl (CPD) radical is dominant, and an intermediate-temperature region from 725 to 850 °C, where a mixture of p-SQ and CPD radicals exists.
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