Reactivity of polonium towards quartz surfaces

Area of Science:

• Radiochemistry
• Nuclear Chemistry
• Superheavy Element Chemistry

Background:

• Polonium (Po) is a highly radiotoxic element with increasing interest due to its presence in accelerator-driven systems.
• Polonium serves as a chemical benchmark for understanding the properties of superheavy elements like livermorium.
• Investigating polonium's chemical behavior is crucial for verifying the structure of the periodic table at its heavy-element frontier.

Purpose of the Study:

• To investigate the gas-solid thermochromatography of polonium at the atom-at-a-time scale.
• To determine the adsorption enthalpies of polonium species on quartz surfaces with varying hydroxylation.
• To elucidate the dominant chemical interactions of polonium under experimental conditions.

Main Methods:

• Gas-solid thermochromatography was performed on polonium in the atom-at-a-time regime.
• Helium and hydrogen gas atmospheres were utilized.
• Quartz surfaces with controlled low and high hydroxyl group (OH) concentrations served as the stationary phase.

Main Results:

• A volatile polonium species with an adsorption enthalpy of -85 kJ mol⁻¹ was identified on low-OH quartz, attributed to elemental polonium.
• A second polonium species, with a higher adsorption enthalpy of -139 kJ mol⁻¹, was observed on high-OH quartz, indicating surface chemical reactions.
• Solid-phase chemical reactions of polonium were found to be dominant over gas-phase reactions.

Conclusions:

• The chemical behavior of polonium is significantly influenced by the surface properties, specifically the degree of hydroxylation.
• Surface chemistry plays a critical role in polonium's interactions, impacting deposition behavior in gas chromatography.
• Future gas chromatography studies involving polonium must carefully consider surface characteristics as a key experimental parameter.