Zi Chen,Dongdong Lu,Hangqing Xie,Xiaolei Yang,Yang Li,Chenhao Bao,Lei Lei,Shiqing Xu
The increasing demand for radiation detection in many applications has led to demanding requirements for scintillators. Realizing low-dose, pollution-free, and reliable X-ray detection has become a key technical challenge. Here, a triplet-enhanced lanthanide radioluminescence (RL) material Ga 3+ /Tb 3+ metallacrowns (Tb-1) is reported. This Tb-1 crystal emits bright green luminescence under ultraviolet light or X-ray excitation, and the emission intensity is 286 and 242 times that of Tb 3+ in inorganic salt, respectively. Tb-1 crystal is further passivated by trioctylphosphine oxide (TOPO), and the enhanced RL intensity is equivalent to that of commercial Tl-doped cesium iodide scintillator. In addition, RL of Tb-1–TOPO has an extremely narrow full width at half maximum and an excellent linear response to the X-ray dose rate. The detection limit is calculated to be 0.146 μGy s −1 , which is 38 times lower than typical medical imaging doses. Triplet-enhanced lanthanide RL provides new ideas for replacing scintillators that require high temperature synthesis processes such as inorganic phosphors and ceramics, and provides a new alternative scintillator material for flexible X-ray monitoring, bioimaging, radiotherapy, and other applications.
Speciation of thallium (Tl) controls its fate and biogeochemical behaviors. Thus, a sensitive and accurately approach for Tl monitoring is of great demand due to its ultra-low concentration and sensitivity to redox change. In this study, diffusive gradients in thin-films technique (DGT) assembled with novel titanium peroxide (TP) binding gels (TP-DGT) was developed for in situ measurement of dissolved Tl(I) and Tl(III) in waters and sediments. Laboratory test showed a linear mass accumulation of Tl(I) and Tl(III) on the TP binding gels with the deployment time from 4 to 72 h. A fascinating performance of this novel DGT was achieved in a pH range of 4–9, ionic strength range of 0.1–200 mmol L −1 , and humic acid concentration of 0–30 mg L −1 with a low detection limit of 0.3 ng L −1 for Tl(I) and 0.6 ng L −1 for Tl(III). The TP binding gels own excellent stability (1–365 d) and high capacity (73.5 μg Tl disc −1 ) which are suitable for long-term monitoring. Field application in a river indicated that TP-DGT could work effectively, comparable to the grab sampling in waters. For the first time, the TP-DGT coupled with oxygen optode was successfully applied to map 2D distribution patterns of Tl and oxygen simultaneously in the rhizosphere of M. verticillatum L. This study confirms TP-DGT is a promising tool for routine monitoring of Tl in waters and for investigating biogeochemical processes of Tl in sediments.
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