Einsteinium electronic structure

As the atomic number increases, the radial extension and the bandwidth of the 5/ electrons decreases. From americium on the 5/ electrons are localized, nonbonding, and carry a magnetic moment. The actinide metals americium to californium and lawrencium are trivalent metals. Einsteinium to nobelium are divalent metals due to very high promotion energies needed to promote one / electron to the metallic bonding state as known from ytterbium in the lanthanide series. Thus, the actinide series displays more complex electronic structures than does the lanthanide series not only in the first half of thek series. 

Actinium and thorium have no / electrons and behave like transition metals with a body-centered cubic structure of thorium. Neptunium and plutonium have complex, low-symmetry, room-temperature crystal structures and exhibit multiple phase changes with increasing temperature due to their delocalized 5/ electrons. For plutonium metal, up to six crystalline modifications between room temperature and 915 K exist. The / electrons become localized for the heavier actinides. Americium, curium, berkelium, and californium all have room-temperature, double hexagonal, close-packed phases and high-temperature, face-centered cubic phases. Einsteinium, the heaviest actinide metal available in quantities sufficient for crystal structure studies on at least thin films, has a face-centered cubic structure as typical for a divalent metal. 

The high specific radioactivity of einsteinium has greatly limited the investigations of the metal. Of the two attempts to prepare the metal and determine its structure, the successful method employed electron difiraction rather than x-ray diffraction. The latter was largely inconclusive because of degradation of the metal s crystallinity caused by self-irradiation. The electron diffraction lines from 11 samples were indexed on the basis of a face-centered cubic structure with Uq = 0.S7S 0.001 nm [22]. This fee form of einsteinium metal is believed to be... 

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