Fullerenes are one of the more shocking things in chemistry. They are extremely stable structures (spheres, spheroids, tubes, sheets) made out of carbon, an element that’s otherwise so complexly reactive that it’s the basis of organic chemistry which seems to constitute half of all of chemistry. Sixty carbon atoms can be organised into a tiny spherical fullerene shell of great tensile strength (relative to size) that can contain other things. The fullerene is practically non-reactive so it doesn’t react with what’s inside, and what’s inside doesn’t get out because the fullerene is wrapped around it. But that’s a pretty unusual situation – typically they’re just inert blobs that can be found wherever organic material gets burnt.
But fullerenes weren’t the crazy thing I wanted to write about. You know how radiocarbon dating works, right? The carbon floating around in the atmosphere is partly unstable carbon-14 because cosmic rays keep making it, so we can date dead things by looking at their carbon isotope distributions (which started diverging from atmospheric carbon when the thing died because it stopped exchanging carbon with its environment but the carbon-14 kept on decaying into stabler isotopes). And you’ve probably read about how you can drill through thick ice to find very old air trapped in little bubbles and analyze the gas distribution inside to figure things about what the Earth used to be like. This is like a combination of those things and fullerenes.
It’s speculated that the mass extinctions that separate the Permian period from the Triassic period were due to some cataclysmic event, like a big rock from space hitting the planet. When something like that happens there’s a lot of pressure and high temperatures at the place of impact, so lots of unusual things happen. Like atmospheric molecules minding their own business getting rammed into other things at high energies. One particular thing that can happen is a noble gas (which are naturally found in low densities in the air) getting trapped inside a fullerene ball. This is obviously a pretty stable combination – noble gases don’t react much with anything and fullerene doesn’t react much with anything. So at an old impact site you can find fullerene with some helium and argon trapped inside it. And as it happens, like with carbon, the isotope distribution of old, trapped noble gases will be different from the atmospheric stuff. So we can date the gas! The people who wrote this paper did just that, and found supporting evidence for the space-rock theory.
You gotta love how things come together in science. It works, bitches!
