A team of scientists from Berkeley Lab and Los Alamos National Laboratory has overcome some serious obstacles to report the first study characterizing some of the properties of element 99, known as einsteinium. They synthesised less than 250 nanograms of the element and used it to make complex compounds for X-ray absorption and luminescence spectroscopy. The work, published in Nature, has revealed some important new aspects of the actinide elements – those that are too radioactive to occur naturally and are instead created in nuclear reactors.
Einsteinium is a very rare and short-lived element that was discovered in 1952 in the debris from the detonation of the first hydrogen bomb, called Ivy Mike, at the Pacific test site in the US. It is named after Albert Einstein, although it is not known to exist in nature and only exists in the form of two isotopes (253Es and 254Es) which are both highly radioactive with long half-lives. Only small quantities of it are available to researchers, and its use is restricted by its intense self-irradiation.
Einsteinium behaves a lot like the lanthanide elements of the periodic table, which are radioactive transition metals that are only found in the very small amounts needed for experiments. It has a face-centred cubic crystal structure resembling the metallic lanthanides europium and ytterbium and it can form colored compounds in its +3 oxidation state. It is also the only actinide so far to have a +2 state, which is paler pink in aqueous solution.