Detailed synthesis process of selenium species incorporated in the channels of AlPO4-5 zeolite single crystals is reported. X-ray scattering experiments show diffuse planes which can be analyzed in terms of a partial filling of the channels by helical selenium chains. Polarized Raman and polarized absorption spectra confirm that the helical chains are highly aligned along the channel direction, while the rings appear randomly distributed in the channels. The helical chains have a lowest optical absorption band at 2.6 eV that is strongly polarization dependent, while the rings have a lowest absorption band at 3.0 eV that varies slowly with the light polarization. (C) 2003 Elsevier B.V. All rights reserved.