PHOTOPHYSICAL PROPERTIES OF PYRENE IN ZEOLITES - ADSORPTION AND DISTRIBUTION OF PYRENE MOLECULES ON THE SURFACES OF ZEOLITE-L AND MORDENITE

Adsorption of pyrene on the surfaces of zeolites L and mordenite is investigated using photophysical techniques. Although the internal surfaces of both zeolites are polar, their external surfaces may not be the same. A difference is observed for mordenite. No pyrene excimers can be produced in mordenite, while excimers are readily formed in zeolite L. Due to structural constraints, 30-35% of pyrene adsorbed in mordenite cannot be quenched by O2. Rotational movement of pyrene molecules in mordenite is also restricted by the zeolite structure. Laser photolysis produces pyrene cation and anion radicals, the former having a larger yield than the latter in both zeolites.