Yb3+-Tm3+共掺BiOBr纳米晶的近红外上转换发光特性研究

采用水热法合成了Yb³⁺-Tm³⁺共掺BiOBr纳米晶, 研究了其上转换发光性能。在980 nm光激发下, 样品中Tm³⁺离子实现了³H₄→³H₆、¹G₄→³F₄和¹G₄→³H₆跃迁, 进而发出强烈的近红外光(801 nm)和较弱的红光(655 nm)与蓝光(485 nm)。探讨了样品的上转换发光机理, 上转换发光强度与激发功率的关系表明在980 nm激发下Tm³⁺的蓝光和红光发射为三光子过程, 而近红外发光为双光子过程。随着Yb³⁺浓度增加, 近红外发光显著增强, 近红外光与蓝光(I_{801 nm}/I_{485 nm})的发光强度比高达71.4。研究结果表明, Yb³⁺-Tm³⁺共掺BiOBr纳米晶在生物荧光标记领域具有潜在的应用前景。

Near-infrared Upconversion Luminescences Properties of Yb3+-Tm3+ Co-doped BiOBr Nanocrystals

Yb³⁺-Tm³⁺ co-doped BiOBr nanocrystals were successfully prepared by hydrothermal method, and its upconversion luminescence properties was investigated. Under excitation at 980 nm light, an intense near-infrared (801 nm) accompanied by weak red (655 nm) and blue emissions (485 nm) were observed, which were attributed to the ³H₄→³H₆, ¹G₄→³F₄ and ¹G₄→³H₆ transitions of Tm³⁺ ions, respectively. Power dependence studies revealed that blue and red emission resulted from a three-photon process, while the near-infrared emission resulted from a two-photon process, and a possible upconversion mechanism is discussed. As the Yb³⁺ ions concentration increasing, the overall emission intensity increases and near infrared emission is much stronger than red and blue ones. Consequently, the ratios of near-infrared to visible (I_{801 nm}/I_{485 nm}) reaches 71.4. These results indicate that the Yb³⁺-Tm³⁺ co-doped BiOBr nanocrystals have potential applications in biological field as luminescence labeling probers.