Strong explosive interaction of hydrogenated porous silicon with oxygen atcryogenic temperatures - art. no. 068301

We report new types of heterogeneous hydrogen-oxygen and silicon-oxygen bra nched chain reactions which have been found to proceed explosively after th e filling of pores of hydrogen-terminated porous silicon (Si) by condensed or liquid oxygen in the temperature range of 4.2-90 K. Infrared vibrational absorption spectroscopy shows that, while initially Si nanocrystals assemb ling the layers have hydrogen-terminated surfaces, the final products of th e reaction are SiO2 and H2O. Time-resolved optical experiments show that th e explosive reaction develops in a time scale of 10(-6) S. We emphasize the remarkable structural properties of porous Si layers which are crucial for the strong explosive interaction.