Modeling of luminescence-based oxygen sensing by redox-switched energy transfer in nanocrystalline TiO2:Sm3+

Oxygen-Sensitive Photoluminescence of Rare Earth Ions in TiO2 Thin Films

“…Therefore, the defects become energy acceptors capable of quenching Sm 3+ fluorescence. 2 Correspondingly, the PL becomes weaker and its decay kinetics becomes faster, in accordance with Figures 4 and 8. At the same time, the number of initially excited ions is virtually unaffected so that the initial PL intensity immediately after the exciting laser pulse remains unchanged.…”

“…Yet, the observed oxygen sensitivity of the TiO 2 :Sm 3+ emission is completely in line with the published data on the sol−gel material of similar composition. 2,13 The proposed model presumes that the free electrons captured by adsorbed O 2 species are effectively taken from certain lattice defects. As a result, the energy levels of the defects are altered in such a way that their electronic transitions become resonant with Sm 3+ transitions.…”

“…In particular, the studies of oxygen-sensitive PL of TiO 2 :Sm 3+ , mostly in the form of sol−gel-prepared nanoparticles, concluded that oxygen adsorption indirectly affects the PL quantum yield of Sm 3+ ions through a charge-transfer mechanism. 2 The latter seems to operate over distances of at least tens of nanometers, based on the morphology of studied samples and achieved relative response. However, it remains unclear whether the mechanism is specific to Sm 3+ dopant or applies to a broader range of extrinsic emitters, and what is the role of heating and UV excitation in activating the oxygen sensitivity.…”

“…In this connection, it is not surprising that the PL intensities of both intrinsic defects , and rare earth impurity ions , in TiO 2 nanomaterials were found to depend significantly on the presence of oxygen in the surrounding atmosphere. In particular, the studies of oxygen-sensitive PL of TiO 2 :Sm 3+ , mostly in the form of sol–gel-prepared nanoparticles, concluded that oxygen adsorption indirectly affects the PL quantum yield of Sm 3+ ions through a charge-transfer mechanism . The latter seems to operate over distances of at least tens of nanometers, based on the morphology of studied samples and achieved relative response.…”

High-performance photoluminescence-based oxygen sensing with Pr-modified ZnO nanofibers

“…XPS is a surface sensitive technique, so the finding that the measured Pr/Zn atomic ratio (0.11:1.00) is much larger than that in the precursor mixture (0.01:1.00) implies that a large fraction of the Pr is at the surface of (or at the interface between) the ZnO nanocrystallites. The O/Zn atomic ratios derived from the XPS data 7 for the PZNF and ZNF samples are, respectively, 1.57:1.00 and 1:03:1.00indicating that the PZNF sample supports relatively more oxygen containing species on its surface.…”