Ln3+ doped nanoparticles: new optical and magnetic properties

镧系元素（La-Lu）因其光学和磁性而令人着迷，它们的实际应用渗透到我们的社会中（例如强磁铁、核磁共振造影剂）。我的跨学科和多学科研究计划将探索新的方向，所有这些都基于胶体稳定（掺杂）纳米粒子（NPs）：1)单掺杂纳米粒子：在电信窗口中运行的稳定单光子源在光学量子计算和密码学中非常受欢迎。将开发一种方法，在NP中掺杂一个Er3+，其发射波长为1.55微米。这种单掺杂NPs还可以测定一个Er3+离子的光物理性质；2)掺杂NPs的双光子激发光致发光：初步数据表明，Eu3+、Tb3+、Dy3+和Sm3+都可以实现光致发光。这是一个几乎没有被探索过的领域，并有望带来一些新的和令人兴奋的光物理学，例如，有理论工作得出结论，与单光子过程不同，Ln3+离子的双光子在4f内跃迁是允许的。为实现无重叠发射的光学相关光谱铺平了道路；3)上转换（核壳）NPs将两个或多个低能光子转换为一个高能量光子（通常是近红外辐射到红、绿、蓝光）得到了很多研究。然而，量子产量率仍然远低于它们的批量产品，其原因仍然难以捉摸。我假设NPs的低温合成，即300摄氏度左右，会导致内部缺陷，这是主要的淬火部位。将使用维多利亚大学的扫描透射电子全息显微镜（STEHM）。4) MRI相关性：MRI中的造影剂通常通过添加T1或T2造影剂来增强造影剂。如果能研制出“T1-only”和“T2-only”造影剂，似乎可以进行磁共振相关成像。我们有一些数据来支持这个假设；5)磁性NPs作为“单分子磁体”：在过去的二十年里，单分子磁体（smm）领域取得了巨大的进步，但在液氮以上的温度下获得稳定的smm仍然是一个难以解决的问题。我建议制造SmCo2， NdFeB等NPs。应该有可能使这些NPs足够大，并且仍然是一个单一的磁畴，使得阻塞温度高于液氮；6)体内研究（如癌症诊断和治疗）中的x射线剂量量化是一个尚未解决的问题。我建议制造具有T2造影剂的NPs，其不容易受到x射线诱导过程的氧化状态变化的影响，例如Dy3+，以及由x射线诱导的光电子（例如Eu3+，作为造影剂是无效的，Eu2+是一种有效的T1造影剂）激活的T1造影剂。T2对比可作为内部标准。一个内部标准是必要的，因为人们永远不知道有多少NPs在肿瘤中定位，因为异质性。

The lanthanides, elements La-Lu, are fascinating because of their optical and magnetic properties and their practical use permeates our society (e.g. strong magnets, MRI contrast agents). My inter- and multidisciplinary research programme will explore new directions, all based on colloidally stable (doped) nanoparticles (NPs):1) singly doped NPs: stable single-photon sources that operate in the telecommunication window are much sought after for optical quantum computing and cryptography. Methods will be developed to dope a NP with one Er3+, which emits at 1.55 micron. Such singly doped NPs also allow to determine the photophysics of one Er3+ ion;2) photoluminescence through two-photon excitation of doped NPs: preliminary data show that this is possible with Eu3+, Tb3+, Dy3+, and Sm3+. This is a hardly explored field and promises some new and exciting photophysics, e.g. there is theoretical work that concludes that the two-photon intra-4f transition of the Ln3+ ions is allowed, unlike the one-photon process. It may pave the way for optical correlation spectroscopy with non-overlapping emissions;3) upconversion (core-shell) NPs that convert two or more low-energy photons into one of higher energy (usually near-infrared irradiation to red, green, and blue light) are much studied. However, the quantum yields are still much lower than their bulk counterparts, for which the reasons remain elusive. I hypothesize that the low-temperature synthesis, i.e. around 300 degrees C, of the NPs leads to internal defects that are main quenching sites. UVic's scanning transmission electron holography microscope (STEHM) will be used.4) MRI correlation: contrast in MRI is often enhanced by adding a T1 or T2 contrast agent. It seems possible to perform magnetic resonance correlation imaging if “T1-only” and “T2-only” contrast agents can be developed. We have some data to support this hypothesis;5) magnetic NPs as “single molecule magnets”: the field of single molecule magnets, SMMs, has made huge progress over the last two decades, but getting stable SMMs at temperatures above liquid nitrogen remains a formidable unresolved issue. I propose to make SmCo2, NdFeB, and the-like NPs. It should be possible to make these NPs large enough and still a single magnetic domain such that the blocking temperature is above liquid nitrogen;6) the X-ray radiation dose quantification during in-vivo studies (e.g. cancer diagnosis and treatment) is an unresolved issue. I propose to make NPs that have a T2 contrast that is not susceptible to a change in its oxidation state by X-ray induced processes, e.g. Dy3+, and a T1 contrast that is and turns on by X-ray induced photo-electrons (e.g. Eu3+, which is impotent as contrast agent, to Eu2+ which is a potent T1 contrast agent). The T2 contrast then serves as an internal standard. An internal standard is necessary for one never knows how much NPs localize in a tumour because of heterogeneity.