Single-atom-at-a-time adsorption studies of $^{211}$Bi and its precursor $^{211}$Pb on SiO$_{2}$ surfaces

Abstract

In preparation of gas-phase chemical experiments with moscovium (Mc, element 115), we studied the chemical behavior of the short-lived bismuth radioisotope $^{211}$Bi in helium, argon, and oxygen atmosphere. Internal chromatograms were recorded as a function of various parameters including carrier gas type and flow rate, thus characterizing the novel miniCOMPACT detector array. This aids to optimize the conditions for experiments with superheavy elements. The bismuth progeny of $^{219}$Rn deposited on the SiO$_{2}$ surface of the miniCOMPACT via diffusion-controlled deposition. Bismuth showed the expected high reactivity towards the SiO$_{2}$ surface of the miniCOMPACT. Experiments in argon and oxygen atmosphere showed no measurable differences in the deposition distribution of the activity. The intermediate 36-min $^{211}$Pb is a member of the $^{227}$Ac decay chain, feeding the studied bismuth isotope, was taken into account. To extract thermodynamical data from the results, namely the lower limit of the value of the adsorption enthalpy of Bi on SiO$_{2}$, we performed Monte Carlo simulations, adapted to account for the precursor effect, and compared the experimental results to their output. Simulations were also performed for bismuths heavier homologue, moscovium, using a theoretically predicted value for the adsorption enthalpy of this element on SiO$_{2}$. These suggest moscovium to adsorb in the first part of the miniCOMPACT detection array, in line with recent observations.