Near-Infrared-to-Blue Upconversion in Colloidal BaYF5:Tm3+, Yb3+ Nanocrystals
Near-Infrared-to-Blue Upconversion in Colloidal BaYF5:Tm3+, Yb3+ Nanocrystals
复制标题
DOI：
10.1021/cm900313s
复制
发表时间：
2009-05-12
影响因子：
8.6
通讯作者：
Capobianco, John A.
中科院分区：
文献类型：
--
作者：
Vetrone, Fiorenzo;Mahalingam, Venkataramanan;Capobianco, John A.
使用热分解方法合成了掺杂有0.5摩尔% Tm 3+和15摩尔% Yb 3+的四氟化钇钡（BaYF 5）纳米晶体（BaYF 5：Tm 3+，Yb 3+），产生矩形纳米晶体（15 nm x 5 nm），其可以通过称为上转换的过程将近红外光（上）转换为更高能量（例如蓝光）。BaYF 5：Tm 3+，Yb 3+纳米晶体在980 tun激发后的上转换光谱显示，在高激发密度（90 W/cm（2））下，来自（1）G（4）-> H-3（6）跃迁的上转换蓝光发射比红外H-3（4）-> H-3（6）发射更强，这与Tm 3 +/Yb 3+共掺杂纳米材料通常观察到的情况相反。另一方面，红外发射在较低的激发密度（15 W/cm（2））下占主导地位，这表明缺乏激发的Yb 3+离子来进行超过H-3（4）激发态到（1）G（4）激发态的上转换。在激发密度高于57 W/cm（2）的功率依赖性研究中观察到上转换过程的饱和，导致上转换过程所需的预期光子数出现偏差。对BaYF_5：Tm ~（3+），Yb ~（3+）纳米晶体的上转换发光特性进行了分析和讨论。
Tetragonal barium yttrium fluoride (BaYF5) nanocrystals doped with 0.5 mol % Tm3+ and 15 mol % Yb3+ (BaYF5:Tm3+, Yb3+) were synthesized using the thermal decomposition method yielding rectangular-shaped nanocrystals (15 nm x 5 nm) that can (up)convert near-infrared light to higher energies such as blue, via a process known as upconversion. The upconversion spectrum of the BaYF5:Tm3+, Yb3+ nanocrystals, following excitation with 980 tun, revealed that the upconverted blue emission from the (1)G(4) -> H-3(6) transition was more intense than the infrared H-3(4) -> H-3(6) emission at high excitation densities (90 W/cm(2)) contrary to what is normally observed for Tm3+/Yb3+ codoped nanomaterials. On the other hand, the infrared emission dominates at lower excitation densities (15 W/cm(2)) demonstrating a lack of excited Yb3+ ions to carry on the upconversion beyond the H-3(4) excited state to the (1)G(4) excited state. A saturation of the upconversion process was observed in the power dependence studies at excitation densities above 57 W/cm(2), causing a deviation in the expected number of photons required for the upconversion process. The upconversion properties of BaYF5:Tm3+, Yb3+ nanocrystals are elucidated and discussed.