Optical sensing of NO2 in tin oxide nanowires at sub-ppm level

Tin oxide nanostructures are currently considered as promising materials for gas sensing. Some of their physical properties, such as visible light photoluminescence, are still not fully understood and require further investigations. In this work we report on the quenching of tin oxide nanowires photoluminescence induced by nitrogen dioxide adsorption at the ppm and sub-ppm level. The recombination dynamics was investigated by means of time-resolved photoluminescence, finding non-exponential decay profiles. Neither the photoluminescence spectral shape nor the decay rates are found to depend significantly on the nitrogen dioxide concentration, suggesting that the gas-nanostructure interaction resides in a net reduction of the density of states which are responsible for the radiative transitions.