Scintillators have recently attracted increased attention because of their potential applications in various fields, such as medical imaging, security, and nondestructive inspection . However, the response time of commercial scintillators is normally in microseconds or milliseconds only, a property that restricts their practical applications in high-resolution and dynamic X-ray imaging. Here, we report Rb 2 AgCl 3 crystals as an efficient scintillator material with ultrafast response time. The Rb 2 AgCl 3 crystals were found to have a one-dimensional structure and a bright-orange emission peak at 580 nm and a quantum yield of 60.0%. Experimental and computational studies revealed that the strong emission might have originated from self-trapping excitons that resulted into large Stokes shifts and high quantum efficiency. Upon X-ray excitation, the Rb 2 AgCl 3 crystals displayed a fast scintillation decay time of 9.5 ns and achieved a light yield of 18,300 photons MeV −1 . The ratio of light yield to decay time could reach up to 1926 photons MeV −1 ns −1 , which was higher than that of existing commercial scintillators. As a scintillator, Rb 2 AgCl 3 crystals are a promising material with potential applications in dynamic real-time imaging with a high spatial resolution owing to its nontoxicity, good stability, high light yield, and short decay time.
Kai Jiang,Shan Sun,Ling Zhang,Yuhui Wang,Congzhong Cai,Hengwei Lin
Fluorescent carbon dots (CDs) have attracted much attention in recent years because of their superior optical and chemical properties, thus demonstrating many potential applications. However, the previously reported CDs mostly show strong emission only in the blue-light region, and the long-wavelength (i.e., yellow- to red-light) emissions are usually very weak. Such a drawback restricts their further applications, particularly in the biology-relevant fields. Herein, a rare example of N-doped CDs that emit bright-yellow fluorescence (i.e., y-CDs) is reported using 1,2,4-triaminobenzene as carbon precursor. The as-prepared y-CDs exhibit not only respectable emission quantum yield and highly optical stabilities but superior biocompatibility and biolabeling potentials. In addition, the y-CDs are found to show an interesting “ON–OFF–ON” three-state emission with the stepwise addition of Ag+ and cysteine (Cys), indicating potential applications as a bifunctional sensing platform. Thanks to the highly intense emission of y-CDs, the gradual quenching and restoration of their fluorescence with the addition of Ag+ and further Cys could also be observed with the naked eye. More importantly, the ensemble of the y-CDs and Ag+ demonstrates practicability for the highly selective and sensitive detection of Cys in human plasma samples with satisfactory results.
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