- The photoluminescence (PL) dynamics of terbium-exchanged zeolites X was investigated upon laser excitation at 355 nm. The results evidenced the presence of at least two terbium main environments with PL lifetimes varying between 391-411 and 753-770 mus. The two-site nature of terbium distribution in zeolites X permitted a quantitative analysis of the migration process of terbium ions inside the pores and cavities upon dehydration in air at 200 degreesC. Besides the increase of the PL lifetimes with about 30% and 80% compared to those of the hydrated zeolite, a fraction of almost 30% of terbium ions was estimated to migrate from the supercages to the neighboring sodalites or hexagonal prisms. Our results evidenced for the first time the capability of time-resolved luminescence spectroscopy in quantitatively tracking for the intrazeolitic migration of lanthanides. (C) 2004 Elsevier B.V. All rights reserved
