Lyu Ze-Yu, Dong Hao, Yang Xiang-Fei, Sun Ling-Dong, Yan Chun-Hua
Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
J Phys Chem Lett. 2021 Nov 25;12(46):11288-11294. doi: 10.1021/acs.jpclett.1c03409. Epub 2021 Nov 12.
Polarized emission, an inherent characteristic that correlated with structure and morphology, is very sensitive to orientation. For the upconversion (UC) emission of lanthanides, the mechanism of polarization is rarely discussed, and the highly polarized UC emissions are poorly developed. Herein, with the benefit of the strong anisotropic crystal field, well-resolved emissions from lanthanide-doped LiYF crystals were studied, and highly polarized UC emissions from Er and Ho were investigated. With multiple sub-energy level transitions, the UC emissions are classified into two sets, with transition dipoles being either parallel or perpendicular to the -axis of the LiYF crystal. An optical three-dimensional orientation sensor was further investigated, in which the in-plane angle is referenced from the orientation of the transition dipoles. In contrast, the out-of-plane angle can be deduced from the change in the degree of polarization. This research deepens our understanding of the polarized photoluminescence, and it opens up an avenue toward unique UC orientation sensors.
偏振发射是一种与结构和形态相关的固有特性，对取向非常敏感。对于镧系元素的上转换（UC）发射，偏振机制很少被讨论，而且高度偏振的UC发射发展得很差。在此，得益于强各向异性晶体场，研究了镧系掺杂LiYF晶体中分辨良好的发射，并研究了Er和Ho的高度偏振UC发射。通过多个子能级跃迁，UC发射被分为两组，其跃迁偶极矩要么平行于LiYF晶体的c轴，要么垂直于LiYF晶体的c轴。进一步研究了一种光学三维取向传感器，其中面内角度是根据跃迁偶极矩的取向来参考的。相比之下，面外角度可以从偏振度的变化中推导出来。这项研究加深了我们对偏振光致发光的理解，并为独特的UC取向传感器开辟了一条道路。
