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The formation of porous alumina by galvanostatic anodization in selenic acid has been investigated. The influence of the electrolyte concentration on the morphological features and the self-ordering behavior of the porous oxide film has been studied. The best pore arrangement is obtained upon anodization in 0.5 M H 2 SeO 4 . Using chronopotentiometry, gravimetric analysis and FESEM it is shown that the highest degree of pore ordering is caused by an optimal combination of the two mechanisms that lead to pore initiation: mechanical instability and field-assisted dissolution. In addition, by means of Raman spectroscopy it is found that the optical properties of porous alumina anodized in selenic acid do not exhibit parasite effects due to electrolyte incorporation during anodization. Hence, these templates are of great interest to fabricate and investigate functional nanostructures for optoelectronics.Porous anodic aluminum oxide (AAO) is widely used as a matrix or a template for the development of various functional nanostructures for photonic, electronic, optoelectronic, magnetic and biomedical applications. 1-7 For the successful application of AAO templates in functional devices it is extremely important to have control over their geometrical properties such as regularity, pore diameter and pore density. Only a few electrolytes have been reported to produce highly ordered porous alumina structures: sulfuric, oxalic and phosphoric acids. 7-13 Other organic electrolytes (tartaric, malonic, citric and glycolic acids) have also been reported to yield porous AAO. 14-18 However, porous alumina fabricated in these electrolytes is either short-range ordered or requires long processing time and/or very high voltages to obtain porous oxides with regular geometries. Although ordered AAO structures could be produced under a wide window of experimental conditions, 19,20 there still exists a range of geometrical parameters which cannot be achieved in these standard electrolytes. 20 One of the possibilities to overcome this problem is to perform hard anodization, 21,22 but this method demands applying high voltages so a powerful cooling system is needed. Besides, it is only used for the production of thick AAO matrices. Thus, the development of new electrolytes that allow expanding the range of porous alumina matrix properties is essential. In this regard, selenic acid (H 2 SeO 4 ) has been recently suggested as a new self-ordering electrolyte. 23,24 It has been shown that self-ordered porous alumina structures could be rapidly produced (in 1 h) by selenic acid anodization, showing very promising AAO geometrical features: small pores (15-20 nm) and relatively small pore density (9.2 · 10 9 pores cm −2 ).Furthermore, AAO obtained in selenic acid could also be used as a template for the fabrication and investigation of functional structures for optoelectronics. It is known that porous oxides derived from oxalic acid, other carboxylic acids and phosphoric acid are photoluminescent due to the presence of oxygen vacancies and carb...

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