Superheavies

Table 11 illustrates the known closed proton and neutron shells and the predicted closed nuclear shells (shown in parentheses) that might be important in stabilising the superheavy elements. Included by way of analogy are the long-known closed electron shells observed in the buildup of the electronic stmcture of atoms. These correspond to the noble gases, and the extra stabiUty of these closed shells is reflected in the relatively small chemical reactivity of these elements. The predicted (in parentheses) closed electronic stmctures occur at Z = 118 and Z = 168. 

G. Hermann, Superheavy Elements, International Review of Science, Inorganic Chemisty, Series 2, Vol. 8, Butterworths, London, and University Park Press, Baltimore, Md., 1975 G. T. Seaborg and W. Loveland, Contemp. Physics 28, 233 (1987). 

A further group of elements, the transuranium elements, has been synthesized by artificial nuclear reactions in the period from 1940 onwards their relation to the periodic table is discussed fully in Chapter 31 and need not be repeated here. Perhaps even more striking today are the predictions, as yet unverified, for the properties of the currently non-existent superheavy elements.Elements up to lawrencium (Z = 103) are actinides (5f) and the 6d transition series starts with element 104. So far only elements 104-112 have been synthesized, ) and, because there is as yet no agreement on trivial names for some of these elements (see pp. 1280-1), they are here referred to by their atomic numbers. A systematic naming scheme was approved by lUPAC in 1977 but is not widely used by researchers in the field. It involves the use of three-letter symbols derived directly from the atomic number by using the... 

B. Fricke, Superheavy elements, Structure and Bonding 21, 89 (1975). A full account of the predicted stabilities and chemical properties of elements with atomic numbers in the range Z = 104- 184. 

Since the radioactive half-lives of the known transuranium elements and their resistance to spontaneous fission decrease with increase in atomic number, the outlook for the synthesis of further elements might appear increasingly bleak. However, theoretical calculations of nuclear stabilities, based on the concept of closed nucleon shells (p. 13) suggest the existence of an island of stability around Z= 114 and N= 184. Attention has therefore been directed towards the synthesis of element 114 (a congenor of Pb in Group 14 and adjacent superheavy elements, by bombardment of heavy nuclides with a wide range of heavy ions, but so far without success. 

Searches have been made for naturally occurring superheavies (Z = 112-15) in ores of Hg,... 

F. Bosh, A. ElGoresy, W. Kratschmer, B. Martin, B. PovH, R. Nobiling, K. Traxel and D. Schwalm, Z Physik A280, 39-44 (1977) see also C. J. Sparks, S. Raman, H. L. Takel, R. V. Gentry and M. O. Krause, Phys. Rev. Letters 38, 205-8 (1977), for retraction of their earlier claim to have detected naturally occurring primordial superheavy elements. 

Frenking G, Cremer D (1990) The Chemistry of the Nobles Gas Elements Helium, Neon, and Argon - Experimental Facts and Theoretical Predictions. 73 17-96 Frey M (1998) Nickel-Iron Hydrogenases Structural and Functional Properties. 90 97-126 Fricke B (1975) Superheavy Elements. 21 89-144... 

The chemistry of superheavy elements has made some considerable progress in the last decade [457]. As the recently synthesized elements with nuclear charge 112 (eka-Hg), 114 (eka-Pb) and 118 (eka-Rn) are predicted to be chemically quite inert [458], experiments on these elements focus on adsorption studies on metal surfaces like gold [459]. DFT calculations predict that the equilibrium adsorption temperature for element 112 is predicted 100 °C below that of Hg, and the reactivity of element 112 is expected to be somewhere between those of Hg and Rn [460, 461]. This is somewhat in contradiction to recent experiments [459], and DFT may not be able to simulate accurately the physisorption of element 112 on gold. More accurate wavefunction based methods are needed to clarify this situation. Similar experiments are planned for element 114. 

Fricke, B. (1975) Superheavy elements a prediction of their chemical and physical properties. Structureel Bonding, 21,89-144. Eliav, E., Kaldor, U., Schwerdtfeger, P., Hess, B. and Ishikawa, Y. (1994) The Ground State Electron Configuration of... 

Schwerdtfeger, P. (2003) Relativistic Pseudopotentials, in Theoretical Chemistry and Physics of Heavy and Superheavy Elements, Vol. 11 (eds U. Kaldor and S. Wilson), Progress in Theoretical Chemistry and Physics, Kluwer, Dordrecht, pp. 399—438. in references therein. 

Seth, M., Cooke, F., Pehssier, M., Heully J.-L. and Schwerdtfeger, P. (1998) The Chemistry of the Superheavy Elements II. The Stability of High Oxidation States in Group 11 Elements. Relativistic Coupled Cluster Calculations for the Fluorides of Cu, Ag, Au and Element 111. Journal of Chemical Physics, 109, 3935—3943. 

Hancock, R.D., Bartolotti, L.J. and Kaltsoyannis, N. (2006) Density Functional Theory-Based Prediction of Some Aqueous-Phase Chemistry of Superheavy Element 111. Roentgenium (I) Is the Softest Metal Ion. Inorganic Chemistry, 45, 10780-10785. 

Schadel, M. (2003) The Chemistry of Superheavy Elements, Kluwer Academic. Dordrecht. 

Pershina, V., Bastug, T., Sarpe-Tudoran, C., Anton, J. and Fricke, B. (2004) Predictions of adsorption behaviour of the superheavy element 112. Nuclear Physics... 

It should be noted that there is a limited number of works on classical relativistic dynamical chaos (Chernikov et.al., 1989 Drake and et.al., 1996 Matrasulov, 2001). However, the study of the relativistic systems is important both from fundamental as well as from practical viewpoints. Such systems as electrons accelerating in laser-plasma accelerators (Mora, 1993), heavy and superheavy atoms (Matrasulov, 2001) and many other systems in nuclear and particle physics are essentially relativistic systems which can exhibit chaotic dynamics and need to be treated by taking into account relativistic dynamics. Besides that interaction with magnetic field can also strengthen the role of the relativistic effects since the electron gains additional velocity in a magnetic field. 

Superheated steam dryers, 9 138-139 Superheated steam turbines, 26 135-136 Superheating, in vapor-compression refrigeration systems, 21 543-545 SuperHeavy Elements (SHEs), 1 465, 494-499... 

It may be noted that several authors (56,57) have calculated many properties of a rich spectrum of hadrons with few parameters in a phenomenological model. In all of these cases, the quark inside a nucleon has a much smaller effective mass than the free quark outside a nucleon. It has also been discussed (58) whether there exist quasi-stable hadrons containing superheavy quarks with atomic weights around 30. 

Fig. 29. Schematic diagrams showing (a) hexagonal and (b) striped domain wall arrangements (only superlight walls are drawn on a triangular lattice (e.g. the (111) face of f.c.c. metals)). In incommensurate layers, where the monolayer is compressed with respect to the commensurate lattice, domain walls or either heavy or superheavy (c).

The analysis in the last paragraph has shown that the incommensurate Xe layer on Pt(lll) at misfits of about 6% is a striped phase with fully relaxed domain walls, i.e. a uniaxially compressed layer. For only partially relaxed domain walls and depending on the extent of the wall relaxation and on the nature of the walls (light, heavy or superheavy) additional statellites in the (n, n) diffraction patterns should appear. Indeed, closer to the beginning of the C-I transition, i.e. in the case of a weakly incommensurate layer (misfits below 4%) we observe an additional on-axis peak at Qcimm + e/2 in the (2,2) diffraction pattern. In order to determine the nature of the domain walls we have calculated the structure factor for the different domain wall types as a function of the domain wall relaxation following the analysis of Stephens et al. The observed additional on-axis satellite is consistent with the occurrence of superheavy striped domain wails the observed peak intensities indicate a domain wall width of A=i3-5Xe inter-row distances. With... 

Superheavy Elements Island of Stability. LBNL Image Library. http //www.imglib.Ibl.gov. ImgLib/COLLECTlONS/ BERKELEY-LAB/SEABORG-ARCHIVE (accessed October 23, 2005). 

In order to determine the maximum atomic mass produced in the r process, we must find the point when induced (destructive) fission enters into competition with (constructive) neutron capture on the path followed by the process across the (N, Z) map of the isotopes. This question requires calculation of the fission barrier far from the region of known nuclei, which is no simple matter. The possibility of producing mythical, superheavy, transuranium nuclei (around Z = 114 and = 184) has not yet been demonstrated. 

The relativistic coupled cluster method starts from the four-component solutions of the Drrac-Fock or Dirac-Fock-Breit equations, and correlates them by the coupled-cluster approach. The Fock-space coupled-cluster method yields atomic transition energies in good agreement (usually better than 0.1 eV) with known experimental values. This is demonstrated here by the electron affinities of group-13 atoms. Properties of superheavy atoms which are not known experimentally can be predicted. Here we show that the rare gas eka-radon (element 118) will have a positive electron affinity. One-, two-, and four-components methods are described and applied to several states of CdH and its ions. Methods for calculating properties other than energy are discussed, and the electric field gradients of Cl, Br, and I, required to extract nuclear quadrupoles from experimental data, are calculated. 

---