Prediction of the adsorption behavior of elements 112 and 114 on inert surfaces from ab initio Dirac-Coulomb atomic calculations

Abstract

The interaction of elements 112 and 114 with inert surfaces has been studied on the basis of fully relativistic ab initio Dirac-Coulomb CCSD(T) calculations of their atomic properties. The calculated polarizabilities of elements 112 and 114 are significantly lower than corresponding Hg and Pb values due to the relativistic contraction of the valence ns and np(12) orbitals, respectively, in the heavier elements. Due to the same reason, the estimated van der Waals radius of element 114 is smaller than that of Pb. The enthalpies of adsorption of Hg, Pb, and elements 112 and 114 on inert surfaces such as quartz, ice, and Teflon were predicted on the basis of these atomic calculations using a physisorption model. At the present level of accuracy, -DeltaH(ads) of element 112 on these surfaces is slightly (about 2 kJ/mol) larger than -DeltaH(ads)(Hg). The calculated -DeltaH(ads) of element 114 on quartz is about 7 kJ/mol and on Teflon is about 3 kJ/mol smaller than the respective values of -DeltaH(ads)(Pb). The trend of increasing -DeltaH(ads) in group 14 from C to Sn is thus reversed, giving decreasing values from Sn to Pb to element 114 due to the relativistic stabilization and contraction of the np(12) atomic orbitals. This is similar to trends shown by other atomic properties of these elements. The small difference in DeltaH(ads) of Pb and element 114 on inert surfaces obtained within a picture of physisorption contrasts with the large difference (more than 100 kJ/mol) in the chemical reactivity between these elements.

Chemistry of superheavy elements

“…Relativistic calculations, which show a strong stabilization of the closed 7s 2 shell, indicated the possibility that element 112 is rather inert -almost like a noble gas -and, in elementary form, a gas or a very volatile liquid (metal) [141]. Recent calculations [84,[237][238][239] (and [240] with somewhat different results) predict that a very volatile Cn would still retain a metallic character which would allow bond formation with metallic surfaces like Au [84,239]. On inert surfaces, however, no adsorption is expected [84,238].…”

“…Recent calculations [84,[237][238][239] (and [240] with somewhat different results) predict that a very volatile Cn would still retain a metallic character which would allow bond formation with metallic surfaces like Au [84,239]. On inert surfaces, however, no adsorption is expected [84,238]. Empirical extrapolations of sublimation enthalpies gave only 22 kJ/mol [241].…”

“…Hot-fusion reactions are characterized by excitation energies of 35 MeV to 55 MeV when nuclei from 238 U to 249 Cf fuse with beams from 18 O to 48 Ca. Consequently, three to five neutrons are emitted before the compound nucleus has cooled.…”

“…These experiments provided a breakthrough and led to the (only for elements 114 and 116 officially accepted) discovery of elements up to 118 [30,31]; an overview is given in [32,33]. Results from a 48 Ca on 238 U experiment at SHIP [34] support data about the synthesis and decay of 3.8-s 283 Cn [35]. The synthesis of the most neutron-deficient know isotope of element 114, 285 114 (T 1/2 ≈ 0.1 s) [36], was achieved in an experiment at the Berkeley Gas-filled Separator (BGS).…”

“…It was at the Flerov Laboratory of Nuclear Reactions (FLNR) in Dubna where, over the last decade, Oganessian and coworkers carried out large series of experiments irradiating targets ranging from 238 U to 249 Cf with 48 Ca beams. Products were separated with the Dubna Gas-Filled Recoil Separator (DGFRS).…”