PHOTOIONIZATION OF NAPHTHALENE, TRANS-STILBENE AND ANTHRACENE ADSORBED ON THE EXTERNAL AND INTERNAL SURFACES OF ZEOLITES

Laser photolysis of anthracene, naphthalene and trans-stilbene on zeolite NaA and in zeolite NaX produces electrons trapped in Na(n)n+ clusters, singlet and triplet excited states and radical cations of the arenes. Only Na-4(3+) is observed in NaX where the arene is located inside the supercage; however, other trapped species, such as Na-3(2+), are also observed in NaA where the arene is located solely on the external surface. Thermal decomposition of trans-stilbene in NaX produces an unknown brown product, which shortens the lifetime of the electrons trapped in the sodium ionic clusters. The photoionized electrons from arenes on NaA are trapped by sodium cation clusters inside the sodalite cage next to the surface and close to the arene radical cation. No oxygen quenching of the trapped species, Na-3(2+) and Na-4(3+) in the arene-NaA system is observed due to the exclusion of O2 by the small entry pore of the sodalite cage (approximately 2.6 angstrom).