Adsorption effects of NO[sub 2] at ppm level on visible photoluminescence response of SnO[sub 2] nanobelts (original) (raw)
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Light emission properties of tin oxide and zinc oxide nanobelts and nanowires have been investigated by means of continuous wave and time resolved photoluminescence. In both kind of nanostructures, photoluminescence quenching was observed at increasing temperature and at interaction with 5ppm concentration NO2. Photoluminescence time decay measurements in the visible range suggest that adsorbed NO2 induces fast non-radiative relaxation of
Role of surface oxygen vacancies in photoluminescence of tin dioxide nanobelts
The role of surface oxygen vacancies in the optical properties of tin dioxide nanobelts is investigated in this paper. Using a first-principles approach, based on the density functional theory combined to a very accurate exchange correlation functional, we characterize SnO 2 (1 0 1), that is the nanobelt largest surface. We show that the presence of surface oxygen vacancies leads to the appearance of (i) occupied states located at about 1 eV above the valence band and (ii) unoccupied states lying in resonance with the conduction band. Photoluminescence characterization performed on samples of SnO 2 nanobelts at low temperature shows that the basic spectral features of luminescence are in excellent agreement with theoretical predictions.
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New Journal of Physics, 2008
The recent observation of selective photoluminescence (PL) quenching in tin dioxide (SnO 2 ) nanowires (NWs) upon adsorption of nitrogen dioxide (NO 2 ) molecules triggered much interest on possible applications of SnO 2 nanostructures as selective optochemical transducers for gas sensing. Understanding the peculiar gas-nanostructure interaction mechanisms lying behind this phenomenon may be of great interest in order to improve the selectivity of solid-state gas sensing devices. With this aim, we studied the luminescence features of SnO 2 NWs in controlled adsorption conditions by means of continuous wave-and time-resolved PL techniques. We show that, under assumption of a Langmuir-like adsorption of gas molecules on the nanostructures surface, the decrease of PL intensity is linearly proportional to surface density of adsorbed molecules, while the recombination rates of excited states are not significantly affected by the interaction with NO 2 . These findings support a picture in which NO 2 molecules act as 'static quenchers', suppressing emitting centres of SnO 2 in an amount proportional to the number of adsorbed molecules. A simple model based on the above mechanism and allowing good fitting of the data is described and discussed. The possible indirect or direct role of oxygen vacancy states in SnO 2 luminescence is finally discussed.
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MRS Proceedings, 2006
SnO2 nanowires have been recently employed in the “gas-sensors” field and excellent results of conductometric and optical tests on SnO2 nanowires-based gas sensors have been reported.However, the mechanism that controls the gas-sensing effect in metal oxides nanowires is not fully understood yet. Here the authors present the first results of an in-depth study about the influence of post growth treatments on the physical and gas sensing properties of SnO2 nanowires.In particular, SnO2 nanowires grown by a vapour transport technique were annealed in a oxygen-rich atmosphere and then characterized by different techniques to assess the influence of the treatment on the nanowires properties.The annealing in oxygen atmosphere is shown to strongly affect the PL and CL spectra, the electrical resistivity as well as the gas sensing properties of the nanowires. The obtained results are consistent with a reduction of the oxygen vacancies concentration induced by the O2 treatment and seem to co...
Structural and optical study of SnO 2 nanobelts and nanowires
Materials Science and Engineering: C, 2005
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