Scanning Probe Electron AnalyseR (SPEAR)

在电影《蜘蛛侠》中，纳米技术是邪恶的绿妖精手中的一种工具，但在电影《雷鸟》中，特雷西家族也使用了它。因此，就像任何技术一样，纳米技术可以是一种工具，可以是好的，也可以是坏的。当然，这两个例子都是科幻小说。但扫描隧道显微镜(STM)是一种尖尖的针，当它测量表面和针尖之间流动的电流时，它在表面上扫描-是真实世界纳米技术的一个例子(它发明于1982年)，一种可以成像和操纵单个原子的工具。扫描隧道显微镜的问题是，它不能分辨出它看到的是哪种原子。100年前，爱因斯坦解释了光电效应--当你将紫外线或X射线照射到材料表面时，材料中的一些电子会跳出来。这些电子的能谱携带着关于材料组成及其所谓的电子态的信息。如果我们能收集光电子，并用扫描隧道显微镜的尖端测量它们的能量，我们就可以在非常小的范围内分析材料，找出原子的情况。因此，这个项目的目标是在尖端(实际上，在尖端本身)上建造一个微小的电子分析器--我们称之为扫描探针电子分析器，或简称为矛。它将在光线照射时扫描表面，从而测量分辨率低至约10纳米的光电子光谱。这比人类头发的直径和大约30个原子的大小小1000倍。为了建造分析仪，我们必须制造一种特殊的STM尖端，一种以前从未制造过的尖端，但有了合适的人员和先进的设备，我们相信我们可以做到。尖端是由许多层组成的，就像洋葱一样，但它是针形的--这是关键。我们认为，同样类型的微制造尖端也可以用作电子源(而不是分析器)，以实现另一种类型的纳米光谱，即测量发射的电子从表面反弹时的能量损失-这被称为扫描探针能量损失光谱，或SPELS。最后，我们想通过测量小原子团的量子性质来展示这两种新技术的力量，这些原子团的行为方式与我们日常处理的材料截然不同。未来，我们认为这些工具可能会被公司用来解决材料工程中的实际问题。

In the movie Spiderman nanotechnology was a tool in the hands of the evil Green Goblin, but in the Thunderbirds movie the Tracy family used it too. So, like any technology, nanotechnology can be a tool for good or evil. Of course, both examples are science fiction. But the scanning tunnelling microscope (STM) - a sharp needle which scans over a surface as it measures the electrical current flowing between the surface and the tip of the needle - is an example of real-world nanotechnology (it was invented in 1982), a tool which can image and manipulate individual atoms. The problem with STM is that it can't tell what kind of atoms it is seeing. Now, 100 years ago Einstein explained the photoelectric effect - some of the electrons in a material can jump out when you shine UV light or X-rays on the surface. The energy spectrum of these electrons carries information about the composition of the material and its so-called electronic states . If we could collect the photoelectrons and measure their energy with the tip of a scanning tunnelling microscope, we could analyse the material on a very small scale and find out about the atoms. So this project is aiming to build a tiny electron analyser onto the tip (in fact, inside the tip itself) - we call it the Scanning Probe Electron AnalyseR, or SPEAR for short. It will scan over the surface while the light is shining, and so measure the photoelectron spectrum with a resolution down to about 10 nanometres. This is 1000 times smaller than the diameter of a human hair and the size of about 30 atoms. To build the analyser we have to make a special kind of STM tip, a type of tip which hasn't been made before, but with the right people and the advanced equipment we have we believe we can do it. The tip is made of lots of layers like an onion, but it's the shape of a needle - that's the key idea. We think that the same kind of microfabricated tip can also be used as an electron source(rather than an analyser), to make possible another type of nanoscale spectroscopy, where we measure the energy lost by the emitted electrons when they bounce back from the surface - this is called Scanning Probe Energy Loss Spectroscopy, or SPELS. Finally, we want to demonstrate the power of both these new techniques by measuring the quantum properties of small clusters of atoms, which behave in a very different way from the materials we handle everyday. In the future, we think that these tools may be taken up by companies to solve practical problems in materials engineering.