화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.106, No.21, 5413-5420, 2002
Adsorption of radon on metal surfaces: A model study for chemical investigations of elements 112 and 114
The adsorption properties of Rn on polycrystalline surfaces of the transition metals Cu, Ag, Au, Ni, and Pd are investigated experimentally by vacuum thermochromatography. This experimental approach provides a fast separation of short-lived nuclides of volatile elements on clean metal surfaces. The adsorption enthalpies of Rn are quantified from the experimental results using a thermodynamic equilibrium model and a Monte Carlo based kinetic model of mobile adsorption, developed in this work. The experimentally observed strength of Rn adsorption is given by the sequence: Ni > Pd approximate to Cu > Au > Ag. The obtained adsorption data are compared with results from empirical calculations of the weak interaction of closed shell atoms with metallic surfaces. An empirical model, which was developed on the basis of experimental adsorption data of Ne, Ar, Kr, and Xe, is extended in order to calculate the adsorption enthalpies of Rn. An excellent agreement is found between model results and the experimental data for the adsorption of Rn on Ag, Au, Ni, and Pd. Extending the model furthermore to the hypothetically noble-gas such as super heavy elements 112 and 114, their adsorption enthalpies on Cu, Ag, Au, Ni, and Pd are predicted. The results and the experimental approach are discussed in view of the experimental investigation of gas-phase chemical properties of the transactinide elements 112 and 114.