Siloxene: Chemical quantum confinement due to oxygen in a silicon matrix

Siloxene (Si6O3H6) and its derivatives show strong visible luminescence. By applying semiempirical quantum chemical calculations to the siloxene structure, we demonstrate that the presence of oxygen in a planar array of silicon atoms results in molecular orbitals confined to Si rings or chains which are responsible for the luminescence properties. Our results on the optical and vibrational properties of siloxene support earlier experimental results identifying siloxenelike structures as the luminescent agent in porous silicon.