Cai Yangjian, Shang Yunfei, Lu Ming, Jin Dayong, Zhou Jiajia
Institute for Biomedical Materials & Devices (IBMD), Faculty of Science, University of Technology Sydney, Sydney, New South Wales 2007, Australia.
UTS-SUStech Joint Research Centre for Biomedical Materials & Devices, Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen Guangdong 518055, P. R. China.
Nano Lett. 2024 Sep 4;24(35):10915-10920. doi: 10.1021/acs.nanolett.4c02652. Epub 2024 Aug 21.
Upconversion nanoparticles are popular as imaging probes due to their advantages in photostability and controllable emission dimensions. However, upconversion polarization remains largely uncharted with previous reports limited to microstructures. In this work, we report the observation of polarized upconversion emissions from β-NaYF single nanostructures below 100 nm. At the sub-100 nm scale, nanorods, nanodiscs, and nanoplates exhibit distinctive polarization degrees despite the same doping concentrations of lanthanides. We find this varied polarization degree results from the crystallographic orientation of nanostructure in relation to the light field and can be linked to the distinctive emission spectrum profile with varied Stark splitting transition ratios from Er. Our findings provide a comprehensive understanding of the polarization properties of upconversion nanoparticles, revealing a previously unexplored aspect of light emission. This discovery expands our knowledge of upconversion nanoparticles and also opens new possibilities for their use in future imaging and sensing applications, where polarization sensitivity is crucial.
上转换纳米粒子因其在光稳定性和可控发射维度方面的优势而作为成像探针广受欢迎。然而，上转换极化在很大程度上仍未被探索，先前的报道仅限于微观结构。在这项工作中，我们报告了在低于100 nm的单个β-NaYF纳米结构中观察到偏振上转换发射。在亚100 nm尺度下，尽管镧系元素的掺杂浓度相同，但纳米棒、纳米盘和纳米板表现出不同的偏振度。我们发现这种不同的偏振度源于纳米结构相对于光场的晶体取向，并且可以与具有不同铒斯塔克分裂跃迁比率的独特发射光谱轮廓相关联。我们的研究结果提供了对上转换纳米粒子偏振特性的全面理解，揭示了一个以前未被探索的发光方面。这一发现扩展了我们对上转换纳米粒子的认识，也为它们在未来成像和传感应用中的使用开辟了新的可能性，在这些应用中偏振灵敏度至关重要。
