Probing radicals and reactive species in zeolites

Alkyl radicals can play an important role as intermediates in lean NO_x chemistry. This type of chemistry is of relevance to the treatment of emissions from diesel engines. CN radicals have been identified as possible intermediates in a study of the catalytic reduction of propane or ethanol (under lean NO_x conditions over a Cu-ZrO₂ catalyst). However, monitoring radicals and/or other reactive species can involve specialized techniques. Diatomic iodine provides a model system in which the dynamics and interactions of intra-zeolite species can be probed, and where photodissociation leads to two atomic radicals. This work sheds light on how the nanoporous environment of the zeolite can affect photodissociation processes. The polar environment of the zeolite can stabilize states of the parent and photoproducts by interactions that are similar to those involving solvation.