Theoretical Investigations of Trends in Adsorption of the Heaviest Elements on Gold

Elements 112 through 118 are expected to be very volatile due to strong relativistic effects on their valence electrons. Their volatility is to be studied via the gas-phase thermochromatography technique by measuring the adsorption enthalpy, ∆Hads, on gold plated detectors located along the chromatography column (see results for elements 112 and 114 [1,2]). The obtained ∆Hads is then related to the sublimation enthalpy, ∆Hsub, of macroamounts using a linear correlation between these values [1]. Results of our extended cluster calculations [3] have shown that ∆Hads of group 12 and 14 atoms M adsorbed on gold surface can reliably be predicted on the basis of knowledge of binding energies (De) of gold dimers, MAu: the difference in De(M-Aun), where 1 ≤ n ≤ 120, between the adatoms M is kept almost constant independently of the gold cluster size and adsorption position. Accordingly, in this work, we try to estimate ∆Hads of the 7p elements and their 6p homologs, as well as trends in the chemical rows, on the basis of the calculated De(MAu), where M = Tl/113, Pb/114, Bi/115, Po/116, At/117, Rn/118. The calculations were performed with the use of our fully relativistic 4c-DFT method [4] proven to be a reliable tool in predicting binding energies and bond lengths. Very large optimized basis sets including 5g virtual AOs were used. Results of the calculations of the bond lengths (Re) and De are summarized in Table 1.