利用978 nm近红外光激发样品CaF2∶Pb2+,Yb3+, 在室温下观察到二价Pb2+离子在383 nm附近的紫外上转换发光。该发射峰对应于Pb2+离子的3P0→1A1g(1S0)跃迁。瞬态光谱测量结果表明: 在这个材料体系中, Pb2+离子的激发来自于Yb3+离子三聚体的合作敏化。但是随着Pb2+离子掺杂浓度的提高, Yb3+离子三聚体遭到结构性破坏, 导致其合作发光减弱。本文首次利用Pb2+离子掺杂造成Yb3+离子三聚体的结构性破坏, 从而引起合作荧光猝灭, 并对在CaF2基质中因其他二价离子的掺入而造成的Yb3+三聚体合作发光猝灭给予了合理的解释。

At room temperature, the ultraviolet (UV) upconversion emissions from CaF2∶Pb2+, Yb3+ were observed under the excitation of 978 nm near infrared (NIR) laser. The upconversion emission peak is centered at 383 nm, which is ascribed to the 3P0 → 1A1g (1S0) transition of Pb2+ ions. Through the results of transient measurements, the upconversion process of Pb2+ ions is confirmed. The energy transfer process is that three excited Yb3+ ions simultaneously transfer their energy to one Pb2+ ion. With the increasing of Pb2+ concentration, the cooperative luminescence from Yb3+ clusters decreases gradually. In order to explain this phenomenon, we propose a new cooperative luminescence quenching mechanism in this paper, which is originated from Pb2+ induced structure destruction of Yb3+-trimers. The fluorescence quenching in Pb2+ and Yb3+ codoped CaF2 is given a reasonable explanation.