Spatial versus quantum confinement in porous amorphous silicon nanostructures R. B. Wehrspohn, J.-N. Chazalviel, F. Ozanam and I. Solomon Eur. Phys. J. B, 8 2 (1999) 179-193 Published online: 15 March 1999 DOI: 10.1007/s100510050681