The chemical vapor deposition (CVD) of disilane within the diamond lattice of 13 Angstrom supercages in the acid farm of zeolite Y (HY) has been employed to assemble an array of silicon nanoclusters. In this process, Si2H6 molecules are reactively anchored to Bronsted acid sites in dehydrated HY. This reaction is quantitative as indicated by the disappearance of characteristic nu OH modes in FTIR spectra. Controlled thermal treatment of these samples in a closed system induces a series of H-2 elimination reactions to yield encapsulated ''capped'' silicon nanoclusters. The resulting materials are air and water stable and display orange-red photoluminescence at room temperature. The intensity of this photoluminescence is temperature dependent and proportional to disilane loading. The optical absorption-edges of these materials display red-shifts with increasing disilane loading. They display no temperature dependence and are blue-shifted with respect to bulk silicon.