Gas Phase Chemistry Studies Of Carbonyl Complexes Of The Superheavy Element Seaborgium And Its Homologs

The history of Superheavy elements, the development of nuclear physics experimental technology and the influence of relativistic effects on the chemical properties of superheavy elements are described in this thesis. The research methods for gas phase chemistry studies of superheavy elements and the current research state on transactinide elements in China are summed up.Using 252 Cf SF source and ion-induced nuclear reactions as radioisotope generators, volatile carbonyl complexes were synthetized in site in gas phase reactions with CO and short-lived isotopes of group 6 elements. Volatile carbonyls were transported from the recoil transport chamber to Chemical facilities with gas-jet technique. Their gas phase chemical behavious on specific surfaces were measured using isothermal chromatography and thermal chromatography techniques. High-purity germanium detection system and multichannel silicon detectors were used for the radioactive measurement of these short-lived isotopes. In the experiments of the international collaboration, the gas-filled recoil separator GARIS connected with the heavy ion accelerator RILAC were used to separate evaporation residues from the projectile beam and all other types of reaction products. In this way, the negative impact of the beam plasma was avoided, and for the first time synthetized a superheavy element organic complexes. Adsorption enthalpies of Mo(CO)6, W(CO)6 and Sg(CO)6 on quartz surface were deduced to be-38±1 k J/mol,-47±2 k J/mol and-50±2 k J/mol, respectively, by fitting their breakthrough curves with a Monte Carlo simulation program. By comparing with the theoretical calculations, the chemical property of superheavy element Sg was identified to be similar to its homologs, and consistent with theoretical predictions. This was the first chemical study of a superheavy element with its organic complexes instead of its simple inorganic compounds.Laser-ablation matrix-isolation technique has been used to study the reaction mechanism of forming Mo- and W-carbonyls with CO and single metal atom directly. It was deduced that in gas phase reactions the Mo and W atom which in ―cold atom‖ state will catch the surrounding CO molecular and form carbonyls spontaneously, which means this reaction is a ―cold atom‖ reaction rather than a ―hot atom‖ reaction and the center metal atoms don’t need to be with excess kinetic energy. The most stable carbonyls of group 6 elements are the carbonyl complexes with 6 CO, and they are generated by a series of primitive reactions with the coordination number increasing in turn. Furthermore, carbonyl complexes of Tc, Ru and Rh short-lived isotopes were also studied in the experiments with 252 Cf fission source using isothermal chromatography techniques. Their adsorption enthalpies on Teflon surface and the influence of O2 gas on their chemical yields were determined. This study also corroborates perspectives for studying the gas phase chemistry of superheavy elements Bh(107th element), Hs(108th element) and Mt(109element) in a gas volume containing CO.