Figure 4From: Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids Set of illustrations of the pore structure as a function of the pore widening time in nanoporous anodic alumina fabricated in oxalic ((a) top and (b) cross-section views) and in malonic acids ((c) top and (d) cross-section views). Back to article page