Researchers used lasers to probe individual nobelium atoms
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A heavy element’s nucleus is all bent out of shape.
Nobelium — element number 102 on the periodic table — has an atomic nucleus that is deformed into the shape of an American football, scientists report in the June 8 Physical Review Letters. The element is the heaviest yet to have its nucleus sized up.
By probing individual nobelium atoms with a laser, the team gauged the oblong shape of three nobelium isotopes: nobelium-252, -253 and -254. These different forms of the element each contain 102 protons, but varying numbers of neutrons. The shape is not uncommon for nuclei, but the researchers also determined that nobelium-252 and -254 contain fewer protons in the center of the nucleus than the outer regions — a weird configuration known as a “bubble nucleus” (SN: 11/26/16, p. 11).
The measurements are in agreement with previous theoretical predictions. “It nicely confirms what we believe,” says study coauthor Witold Nazarewicz, a theoretical nuclear physicist at Michigan State University in East Lansing.
Elements heavier than uranium, number 92, aren’t found in significant quantities in nature, and must be created artificially. Currently, the heaviest element on the periodic table is number 118, oganesson (SN Online: 2/12/18). But scientists hope to go even bigger, in search of a potential “island of stability,” a proposed realm in which elements are more stable than other heavy elements.
While many superheavy elements decay in just fractions of a second, some theoretical calculations suggest that elements inhabiting this proposed hinterland might persist longer, making them easier to study. Better understanding the heaviest known elements, including the shape of their atomic nuclei, could help scientists gauge what lies just out of reach.
S. Raeder et al. Probing sizes and shapes of nobelium isotopes by laser spectroscopy. Physical Review Letters. Vol. 120, June 8, 2018, p. 232503. doi:10.1103/PhysRevLett.120.232503.
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