2018-08-01

Third Paper: "Phonon-Polariton Mediated Thermal Radiation and Heat Transfer among Molecules and Macroscopic Bodies: Nonlocal Electromagnetic Response at Mesoscopic Scales"

My third paper has been published! It is in volume 121, issue 4 of Physical Review Letters, and an older preprint of it is available too for those who don't have access to academic journals (it has all of the same figures and ideas, though it is missing a few sentences of further explanation as well as a couple of new citations that were inserted for the final publication). As with my previous papers, in the interest of explaining these ideas in a way that is easy to understand, I am using the ten hundred most used words in English (except for the two lines that came before this one), as put together from the XKCD Simple Writer. I will use numbers sometimes without completely writing them out, use words for certain names of things without explaining further, and explain less used words when they come up. Keep reading to see what comes next.

In the paper that came before this one, I looked at how to do a better job of figuring out the van der Waals (vdW) forces, which are the forces that let geckos (small animals with hard skin over which your finger can slip easily) stick to anything no matter what it is made of, between molecules, which are the little things that make up most of the stuff we see and are in turn made of smaller things called atoms. I tried to figure out how these forces look at distances where the fact that molecules are made of atoms is important, but if those molecules are near much larger bodies, the fact that the larger bodies are made of atoms and molecules should be less important; it turns out that at those distances, how fast light goes matters a lot, and using ways to figure out these forces exactly instead of using easier ways to figure out those forces makes a big change in what those forces are. That paper was able to show how to bring together all of these different ideas from considering large and small bodies in a single way where none of those ideas can be ignored. That would be important when considering new kinds of molecules like graphene, which is made of a lot of carbon atoms in a thin sheet, or really long molecules like DNA or those found in foods, when those molecules are near larger bodies that we make.

This paper looks at the same sorts of molecules, but not at vdW forces anymore. Instead, in this paper, I look at how heat (through light) goes between different molecules, especially when they are near larger bodies. For that, I need to do a better job of considering how molecules can make changes on each other through light, and that means that I need to better consider how the full atoms within molecules move toward and away from each other in a way that repeats itself. By doing that, I can now show how heat through light goes between different molecules, whether they are close together or far away from each other. When people considered heat going through light between larger bodies, they found that the heat would keep growing as the bodies came closer together, and that growing wouldn't stop; from knowing how things work every day, we know that once bodies come close enough, they touch each other, and the growing stops at some point. In this paper, I've shown that when molecules come close together, the heat grows for a while, but if they come close enough, that growing does stop, so I've been able to show what distance we can say two molecules touch each other, so that heat going between molecules happens through them touching instead of through light. This is really important for things like graphene, which are used as part of things used for making power from the sun by getting its light and heat, and also for making new things that can become part of computers made of really small things like molecules that work because of heat going between different parts.

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