Nanocrystal quantum dots and interfaces

在蓬勃发展的纳米技术领域，我们仍然处于这种小规模工具开发的起步阶段。这些工具与周围环境的相互作用，包括比工具本身更大的复杂分子（！），并没有得到很好的理解。我们感兴趣的工具是由半导体制成的纳米晶体，这些纳米晶体非常小，可以在一张纸的边缘上放上一万多个。它们也被称为量子点，以强调它们的行为如何受量子力学定律的支配。从这个意义上说，它们的行为就像人造原子，我们可以设计这些特性，最终导致新材料。然而，我们没有相当于元素周期表的东西来指导我们纳米晶体如何相互作用以及与其他分子相互作用。在本研究计划中，我们将通过两种不同的方式收集更多关于这些相互作用的信息。首先，我们将研究嵌入不同半导体中的量子点，并将其放置在距离其表面不同的距离处。由于半导体-半导体界面具有众所周知的特性，这将使我们能够研究暴露在空气中的表面所起的作用。然后，我们将通过在其上添加不同的物质来控制表面环境，以观察量子点如何与物质相互作用。为了观察这些效应，我们将监测量子点发出的光的光谱。其次，我们将研究直接暴露于配体层（与纳米晶体结合的分子）然后暴露于外部环境的纳米晶体。同样，我们将控制环境并观察不同配体的作用，但为了获得更精确的信息，我们将一次观察一个化合物的发射光谱。这项工作的结果将帮助其他纳米技术专家确定他们遇到的问题是否是由于与外部环境的相互作用，并找到解决这些问题的方法。此外，我们的研究可能会对生物学产生影响，纳米晶体就像灯塔一样被用来发现生物分子，否则这些分子是不可见的。从长远来看，我们的研究在生命科学中的应用可以帮助改善加拿大公民的健康。

In the blooming field of nanotechnology, we are still in the infancy of tool development at this small scale. The interaction of these tools with the environment surrounding them, including complex molecules which can be bigger than the tool itself (!), is not well understood. The tools we are interested in are nanocrystals made of semiconductors which are so small that one could fit more than ten thousands of them on the edge of a piece of paper. They are also called quantum dots to underline how their behavior is governed by the laws of quantum mechanics. In this sense, they behave like artificial atoms for which we can engineer the properties eventually leading to novel materials. However, we don't have the equivalent of a periodic table of elements to guide us on how the nanocrystals interact together and with other molecules. In this research program, we will gather more information on these interactions by two different ways. First, we will look at quantum dots embedded in a different semiconductor and placed at various distances from its surface. As the semiconductor-semiconductor interface has well-known properties, this will allow us to study the role played by the surface exposed to air. We will then control the surface environment by adding different substances on it to see how the quantum dots interact with the substances. To observe these effects, we will monitor the spectrum of the light emitted by quantum dots. Second, we will study nanocrystals which are directly exposed to a layer of ligands (molecules bonding with the nanocrystals) and then the external environment. Again we will control the environment and observe the effect of different ligands, but to obtain more precise information, we will look at the emission spectrum of one nanocrystal at a time. The results of this work will help other nanotechnologists determine if the problems they encounter are due to an interaction with the outside environment and find ways to solve these problems. Moreover, our research is likely to have an impact in biology where nanocrystals are used like a light beacon to find biomolecules which would otherwise be invisible. In the long-term, applications of our research in the life sciences could help improve the health of Canada's citizens.