It is reported that annealing of oxidized porous silicon in water vapor at about 250 °C drastically enhances its blue emission. Infrared absorption studies indicate that this annealing increases all the absorption peaks related to O–H vibrations, except for that of free silanol which disappears completely. No traces of carbon-related signals are observed. The latter result makes a clear objection to blue-band luminescence models based on adsorbed carbon compounds. Although the possibility of silanol-related origins cannot be ruled out, we suggest that some passivation effect of adsorbed hydroxyls on Si nanostructures surrounded by SiO2 is also likely.

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Photochemistry Photochemistry O 0160Oxidation of Alkanes with Dioxygen Induced by Visible Light and Cu(II) and Fe(III) Chlorides. -Liquid phase oxidation of cyclohexane (I) and adamantane (IV) by visible light irradiation in the presence of CuCl 2 or FeCl 3 catalyst yields the corresponding alcohols and ketones. Oxidation of the alkanes (I) and (IV) occur independently with CuCl 2 while the reaction with FeCl 3 is likely to proceed via activation of the solvent. Alkyl hydroperoxides are the primary reaction products and the ratio of their decomposition to alcohols and ketones depends on the catalyst used. Further characteristics like rate of oxygen uptake, carbon dioxide liberation, isotope effect, and radical inhibitor effect are investigated as well. -(TAKAKI*, K.; YAMAMOTO, J.; MATSUSHITA, Y.; MORII, H.; SHISHIDO, T.; TAKEHIRA, K.; Bull. Chem. Soc. Jpn. 76 (2003) 2, 393-398; Dep. Chem. Chem. Eng., Grad. Sch. Eng., Hiroshima Univ., Higashi-Hiroshima 739, Japan; Eng.) -H. Hoennerscheid