Beurer Eva, Grimm Judith, Gerner Pascal, Güdel Hans U
Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland.
J Am Chem Soc. 2006 Mar 15;128(10):3110-1. doi: 10.1021/ja0567790.
Tm2+ doped in CsCaI3 displays unusual optical properties that are characterized by the existence of two metastable 4f-5d excited states in the near-infrared and visible spectral region, respectively. For the first time, a photon upconversion process based on sequential absorption of light by 4f-5d states is reported. The large absorption cross-section of the involved transitions allows highly efficient pumping in the NIR. An efficiency of 11% for the green upconversion luminescence is reached at 10 K, and the upconversion luminescence remains visible by eye up to room temperature. The energy positions of the relevant 4f-5d states and thus the photophysical and light emission properties can be tuned by chemical variation, such as placing the Tm2+ ion into the isostructural CsCaBr3 and CsCaCl3 lattices.
掺杂在CsCaI3中的Tm2+表现出不同寻常的光学特性，其特征是在近红外和可见光谱区域分别存在两个亚稳4f-5d激发态。首次报道了基于4f-5d态顺序吸收光的光子上转换过程。所涉及跃迁的大吸收截面允许在近红外区域进行高效泵浦。在10 K时绿色上转换发光效率达到11%，并且上转换发光在室温下肉眼仍可见。相关4f-5d态的能量位置以及光物理和发光特性可以通过化学变化来调节，例如将Tm2+离子置于同结构的CsCaBr3和CsCaCl3晶格中。
