Wednesday, March 9, 2011

An Excessively Nerdy Post About Spectra

Recently I've been doing a lot of ellipsometry. Ellipsometry reflects a laser off of a thin film and measures how the phase of the horizontal and vertical polarizations change after reflection. If you do it right, this gives you information about how thick the thin film is and what its index of refraction is. Part of ellipsometry is being able to look at a graph of n and k (the real and imaginary parts of the refractive index) and to identify different processes that are happening in the material. A good ellipsometer scientist can look at an n and k spectrum of Gold and say, "Oh those are free electrons over there and over on this part of the spectrum that's two different electron transitions." They can look at a spectrum and extract lots of information from it.

Here's a great example. For no particular reason, I went to Google and typed the letter a, wrote down how many Google hits it had, then moved on to typing aa, et cetera, all the way to 100 a's.

Lots of information can be extracted from this graph.

The first and most obvious piece of information should be the that Jon Banks has lots of patience and/or is incredibly obsessive over proving a point. This is pretty evident in the amount of time it would take to perform this study.

You can also look at the graph and learn about how people tend not to like to hold down the "a" key for all that long. They get tired of it eventually. This is indicated by the general downward trend, decreasing toward zero. However, there's always some freak that holds the "a" key for 5 days and then posts it somewhere.

If you look at a^72 there's a huge spike. Normally, my first guess would be that it is an outlier. But if you go to Google and type 72 a's, you will find that there are quite a few hits at that particular number of a's. So it is consistent, therefore it is real. This indicates to me that a particular group of people is incredibly obsessed with 72 a's. Or maybe some amazing video on youtube has a comment with 72 a's.

One of my favorite parts of experimental physics is looking at a spectrum and extracting all kinds of information from it.

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