Probing electronic structure in berkelium and californium via an electron microscopy nanosampling approach

Due to their rarity and radioactive nature, comparatively little is known about the actinides, particularly those with atomic numbers higher than that of plutonium, and their compounds. In this work, we describe how transmission electron microscopy can provide comprehensive, safe, and cost-effective characterization using only single nanogram amounts of highly-radioactive, solid compounds. Chlorides of the rare elements berkelium and californium are dropcast and then converted in situ to oxides using the electron beam. The f-band occupancies are probed using electron energy loss spectroscopy and an unexpectedly weak spin-orbit-coupling is identified for berkelium. In contrast, californium follows a jj coupling scheme. These results have important implications for the chemistries of these elements and solidify the status of californium as a transitional element in the actinide series.

Properties of the tetravalent actinide series in aqueous phase from a microscopic simulation self-consistent engine

Classical molecular dynamics hydration study for the An(iv) series performed using an automated iterative ab initio based engine.

Viatscheslaw Romanoff: unknown genius of the periodic system

The history of chemistry has not once seen representations of the periodic system that have not received proper attention or recognition. The present paper is dedicated to a nearly unknown version of the periodic table published on the occasion of the centenary celebration of Mendeleev’s birth (1934) by V. Romanoff. His periodic table visually merges Werner’s and Janet’s periodic tables and it is essentially the spiral periodic system on a plane. In his 1934 paper, Romanoff was the first one to introduce the idea of the actinide series, a decade before Glenn T. Seaborg, the renowned creator of the actinide concept. As a consequence, another most outstanding thing about Romanoff’s paper occurs towards its very end: he essentially predicted the discovery of elements #106, #111 and #118. He theorized that, had uranium not been the “creative limit”, we would have met element #106, a “legal” member of group 6, element #111, a precious metal, “super-gold” and element #118, a noble gas. In 2019, we take it for granted that elements #106, #111 and #118 indeed exist and they are best known as seaborgium, roentgenium and oganesson. It is fair to say that Romanoff’s success with the prediction of correct placement and chemical properties of seaborgium, roentgenium and oganesson was only made possible due to the introduction of an early version of the actinide series that only had four elements at that time. Sadly, while Professor Romanoff was imprisoned (1938–1943), two new elements, neptunium (element #93) and plutonium (element #94) were discovered. While Professor Romanoff was in exile in Ufa (1943–1953), six further elements were added to the periodic table: americium (element #95), curium (element #96), berkelium (element #97), californium (element #98), einsteinium (element #99) and fermium (element #100). The next year after his death, in 1955, mendelevium (element #101), was discovered. Romanoff’s version of the periodic table is an unparalleled precursor to the contemporary periodic table, and is an example of extraordinary anticipation of the discovery of new chemical elements.

Theoretical studies on the oxidation states and electronic structures of actinide-borides: AnB12 (An = Th–Cm) clusters

The electronic structures of actinide metal doped half sandwich AnB12 (An = Th to Cm) clusters are explored and characterized using relativistic density functional theory. The trend of oxidation state across the actinide series in AnB12 exhibits two turning points, +V in Pa and +II in Am.