What am I doing here?

A suggested that no one knows why I'm actually here, so I (E) thought I'd take a minute to tell you what I'm up to. I'm working at EMPA, which according to their website is "an interdisciplinary research and services institution for material sciences and technology development." There is a broad range of materials research going on here, not only across the institute but even in my lab. Some people are working on developing new materials for medical devices (hips, knees, etc., trying to make them have a life time of 100 years so that you get the surgery once and never have to think about it again). Others are working on devices to take the waste heat out of car tailpipes and convert it into electrical energy that could, for example, recharge the battery.

I'm working much more on the basic science end of things. In a nutshell, I'm trying to develop a way of measuring fluctuations at the atomic scale by looking at dissipation. The translation of that sentence is a little longer.  First, fluctuations:  any system when it is near a transition will have fluctuations. Think about water freezing.  You might think it just freezes, but those atoms that are on the edge of freezing go through a process of thinking "well, should we turn into ice?  I'm not sure, it is pretty nice being able to flow all over the place rather than being locked into that big ice cube.  But we are pretty tired (it's getting cold outside) so maybe we should..."  They dither a while -- this is (in an obviously cartoony fashion) what a fluctuation is.  Why do we care? Because the nature of the fluctuations -- how fast they are, over what range of parameters they exist, and so forth -- depends on what is causing the transition. So for systems where we don't understand WHY a system is changing from one thing to another (for example, why high temperature superconductors suddenly let current flow through them without any resistance), looking at those fluctuations can help us understand.

The frustrating (and exciting) thing about this is that currently we don't have a good way of measuring these fluctuations. They tend to be very fast and can be spatially dependent, so you have to look closely and quickly to see what is going on. Fortunately, the technique I use, atomic force microscopy, lets us do just that. In AFM we take a very sharp tip and put it on the end of a small cantilever. It looks a lot like an old fashioned record player arm and needle, except shunk down to smaller than a human hair. Because it is so small it vibrates very quickly (up and down a million times a second). We can actually watch how it vibrates (how fast and how much) by watching the wiggles of a laser beam that we bounce off of it.  Anyway, here is the neat thing: if we bring this oscillating cantilever close to some material it slows down -- it both oscillates more slowly and not as much. You can imagine this happening by holding your arm out straight and shaking it up and down, then letting it come into contact with a surface -- it is going to slow down. Try bringing your hand up against a table, for example, or against a sofa. It behaves differently. If there are fluctuations in the material it turns out that they will slow it down more. Those water molecules on the edge of freezing say "Hey! Here is our opportunity to stay warm a little longer if we take the energy from this big tip shaking above us and not freeze" while the ones that are already frozen or far from it don't care so much so don't steal as much energy from the cantilever. So we have a way of measuring the fluctuations.

Well, I was optimistic when I started writing this, but I'm not sure my cartoon is enough to make any of this make any sense. Suffice to say we have a brand new way of measuring something that no one has been able to measure before and lots of people have wanted to and it should allow us to better understand all sorts of new material properties that are right now completely mysterious to us.  If I could just make it work...

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