Modak Monami Das, Damarla Ganesh, Maity Somedutta, Chaudhary Anil K, Paik Pradip
School of Engineering Sciences and Technology, University of Hyderabad Hyderabad 500 046 Telangana India.
Advanced Center of Research in High Energy Materials, University of Hyderabad Hyderabad Telangana 500 046 India.
RSC Adv. 2019 Nov 22;9(65):38246-38256. doi: 10.1039/c9ra06389g. eCollection 2019 Nov 19.
This work reports new findings on the formation of a pearl-necklace pattern in self-assembled upconverting nanocrystals (UCN-PNs) which exhibit strong upconversion emission under an NIR excitation source of a femtosecond laser (Fs-laser). Each nano-necklace consists of several upconversion nanoparticles (UCNPs) having a size 10 ± 1 nm. UCN-PNs are arranged in a self-organized manner to form necklace type chains with an average length of 140 nm of a single row of nanoparticles. Furthermore, UCN-PNs are comprised of UCNPs with an average interparticle separation of 4 nm in each of the nanonecklace chains. Interestingly, these UCN-PNs exhibit high energy upconversion especially in the UV region on interaction with a 140 Fs-laser pulse duration at 80 MHz repetition rate and intense blue emission at 450 nm on interaction with a 900 nm excitation source is obtained. The preparation of self-assembled UCNPs is easy and they are very stable for a longer period of time. The emission (fluorescence/luminescence) intensity is very high which can make them unique in innumerable industrial and bio-applications such as for disease diagnosis and therapeutic applications by targeting the infected cells with enhanced efficiency.
这项工作报道了关于自组装上转换纳米晶体（UCN-PNs）中珍珠项链图案形成的新发现，这些纳米晶体在飞秒激光（Fs-激光）的近红外激发源下表现出强烈的上转换发射。每个纳米项链由几个尺寸为10±1纳米的上转换纳米颗粒（UCNPs）组成。UCN-PNs以自组织方式排列，形成项链型链，单排纳米颗粒的平均长度为140纳米。此外，UCN-PNs由纳米项链链中平均颗粒间距为4纳米的UCNPs组成。有趣的是，这些UCN-PNs在与80 MHz重复频率、140飞秒激光脉冲持续时间相互作用时，尤其在紫外区域表现出高能上转换，在与900纳米激发源相互作用时，在450纳米处获得强烈的蓝色发射。自组装UCNPs的制备很容易，并且它们在较长时间内非常稳定。发射（荧光/发光）强度非常高，这使得它们在无数工业和生物应用中独一无二，例如通过更高效地靶向感染细胞用于疾病诊断和治疗应用。
