How big is a helium atom? Or maybe the better question is: How small? After an intricate game of particle jockeying, physicists have now measured the radius of the helium nucleus five times more ...
Helium atom precision measurements and calculations have a history of nearly a century. In the 1960s, theorists discovered that the fine-structure split (23P0-23P2) of the 23P energy level of helium ...
In a feat of modern-day alchemy, atom tinkerers have fooled hydrogen atoms into accepting a helium atom as one of their own. The camouflaged atom behaves chemically like hydrogen, but has four times ...