Species of dissimilar volatility (adsorbability) can be separated by a technique, which resembles the common gas–solid thermochromatography
but is performed in evacuated columns. The negative longitudinal temperature gradient gives rise to an effective convectionless
molecular flow and the gradually slower migration of the analyte results in a deposit within individual temperature range.
The technique can serve some specific needs of separation of very small amounts of radiolabeled molecular entities (even single
atoms). It also allows evaluation of desorption energies of such molecules from surfaces on the basis of a proper theory of
the separation processes. The paper provides correct prescriptions for the Monte Carlo simulations of the migration of molecules
in columns and of the deposit profiles, which are yet lacking. Numerous performed simulations give better understanding of
influence of various experimental parameters on the data. Possibility, as well as limitation, of using the diffusion ansatz
of the random flights for evaluation of desorption energies is discussed.
Earlier found correlations between the adsorbability of microamounts of compounds and their volatility in macroamounts plus the recently revealed surprisingly strict and general correlation between boiling points and solely geometric parameters of molecules allow to measure fundamental properties of compounds of short-lived man-made transactinoid elements using thermochromatographic principles. Some general topics concerning the separation method are discussed.
Authors:A. Yakushev, S. Timokhin, M. Vedeneev, Xu Honggui, and I. Zvara
An isotope of element 106, namely263106, detected by its spontaneous fission, has been chemically isolated by thermochromatography of oxochlorides. The last one has been compared with short- and long-lived isotopes of Mo and W. Two chemical species were observed, presumably MO2Cl2 and MOCl4 (M=Mo,W). A kinetic dependence of these two species has been discussed and a chemical form O2Cl2 has been described for the registered atoms of element 106.
Authors:B. Zhuikov, V. Glebov, V. Nefedov, and I. Zvara
Using the relativistic multiconfigurational Dirac-Fock method, the first four ionization potentials of Ku, the promotion energies of the atom, and the atomic and ionic radii were calculated. The enthalpy of sublimation of metallic Ku was estimated. Relativistic SCF-X scattering wave Dirac-Slater computations of the tetrachlorides of group IV elements were performed. The lower halides of Ku are predicted to be more stable and less volatile than the respective Hf compounds, due to the ds2 p ground state in the Ku atom.
Authors:S. Timokhin, A. Yakushev, Honggui Xu, V. Perelygin, and I. Zvara
For the first time the chemical identification of element 106 was accomplished. The Gas-thermochromatographic experiments with an oxochloride of element 106 are described. Reproducible zones of tracks of fission fragments were observed in the temperature region of 150–250°C. The chemical behavior of element 106 oxochloride is similar to that of the tungsten compound.
Authors:E. Fedoseev, M. Aizenberg, S. Timokhin, S. Travnikov, I. Zvara, A. Davydov, and B. Myasoedov
Volatile hexafluoroacetylacetonates of hafnium, ytterbium, scandium, as well as scandium trifluoroacetylacetonate and acetylacetonate have been obtained by interaction of -diketone vapours with radionuclides formed in a cyclotron in on-line operation. The application of volatile -diketonates for transport and separation of the short-life isotopes of metallic elements has been shown.
Authors:E. Fedoseev, M. Aizenberg, S. Timokhin, S. Travnikov, I. Zvara, A. Davydov, and B. Myasedov
Volatile hexafluoroacetylacetonates of mendelevium and daughter fermium were first obtained by the interaction of hexafluoroacetylacetone with256Md radionuclide formed in the cyclotron under on-line conditions as well as by the heterophase exchange of ligands. Thermochromatographic behaviour of the complexes synthesized was studied in a flow of a carrier-gas saturated with ligand vapours.
Authors:Z. Szeglowski, H. Bruchertseifer, V. Brudanin, G. Buklanov, O. Constantinescu, Dinh Lien, V. Domanov, L. Guseva, M. Hussonnois, G. Tikhomirowa, I. Zvara, and Yu. Oganessian
Some short-lived isotopes of Hf, Ta and W, synthesized at the U-400 cyclotron of JINR-Dubna, have been isolated using a previously elaborated fast continuous method of chemical isolation of element 104 from nuclear reaction products. The products were transported by a NaCl aerosol jet, from the irradiated targets to a separation device in which Hf, Ta and W were isolated by using three coupled ion-exchange columns.
Authors:Z. Szeglowski, H. Bruchertseifer, V. Brudanin, G. Buklanov, O. Constantinescu, Dinh Thi Lien, V. Domanov, L. Guseva, M. Hussonnois, G. Tikhomirova, I. Zvara, and Yu. Oganessian
The short-lived isotopes of W and their descendants have been isolated from the products of the bombardment of144Sm with24Mg by a fast continuous ion-exchange method, using HF solution media. The feasibility of this method for isolation of element 106 is discussed.