Friday, April 1, 2022

Muonic helium

Happy April. I didn't and, really, don't have anything recent. ToughSf twitter did point us to a new exotic nucleus - more precisely, ion. Here a helium atom with a mu-lepton taking the place of the usual electro-lepton (or unusual antiproton).

The muon (like the antiproton) being so much more massive than the electron, it sinks to a lower quantum "orbit". For as long as the muon lasts (I'll get to this), the helium atom is now - chemically - an extremely heavy hydrogen atom. In the meantime researchers use this atom's odd setup to constrain the charge-radius of the helium nucleus. Which has its own interest since the helium nucleus is (1) the second-most common molecule in the universe, I think and (2) emitted as Alpha Radiation.

Now, er. The muon's lifespan. I'd wondered if some actual chemists might get some play out of this monster pseudohydrogen (E.G. 3/12/22 rockets). When I looked up the lifespan of a free muon: it looked assez, très, troup short-lived. Microseconds, I think. Even milli- wouldn't be good for most reactions. I suppose it might (seem to) last longer if pushed to relativistic speed or gravity, but if you can do that why are you even looking at chemistry?

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