Scanning Probe Electron AnalyseR (SPEAR)

在电影《蜘蛛侠》中，纳米技术是邪恶的绿色妖精手中的工具，但在《雷鸟》电影中，特蕾西一家也使用了它。因此，像任何技术一样，纳米技术可以是善或恶的工具。当然，这两个例子都是科幻小说。但是扫描隧道显微镜（STM）-一种在测量表面和针尖之间流动的电流时扫描表面的锋利针-是现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。STM的问题是它不能分辨它看到的是哪种原子。现在，100年前爱因斯坦解释了光电效应-当你用紫外线或X射线照射材料表面时，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成分及其所谓的电子状态的信息。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，我们就能在很小的尺度上分析材料，并找出原子。因此，这个项目的目标是在针尖上（实际上，在针尖本身内部）建造一个微型电子分析仪-我们称之为扫描探针电子分析仪，简称SPARK。它会在光线照射时扫描表面，因此可以测量光电子光谱，分辨率低至约10纳米。这比人类头发的直径小1000倍，大小约为30个原子。为了建造分析仪，我们必须制造一种特殊的STM针尖，这种针尖以前从未制造过，但有了合适的人员和先进的设备，我们相信我们可以做到。针尖像洋葱一样由很多层组成，但它是针的形状-这是关键的想法。我们认为，同样类型的微加工尖端也可以用作电子源（而不是分析仪），使另一种类型的纳米级光谱学成为可能，在那里我们测量发射的电子从表面反弹时损失的能量-这被称为扫描探针能量损失光谱学，或SPELS。最后，我们希望通过测量小原子团簇的量子特性来展示这两种新技术的力量，这些原子团簇的行为方式与我们日常处理的材料非常不同。在未来，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.