Effect of Temperature on Sodium Perchlorate Radiolysis under Extraterrestrial Conditions

Perchlorates have been found in the regolith of Mars and the Moon, in Europa’s ice, and in meteorites. Understanding how these compounds are destroyed at different temperatures is important for revealing the geological and climatic evolution of the planets and other bodies in the Solar System, as well as assessing their habitability. Here, we present the results of experiments on the radiolysis of sodium perchlorate NaClO4 at temperatures of 133 and 208 K. As the temperature increases, our results show that the amount of perchlorate destroyed and the radiolysis effectiveness increase. We detected the formation of secondary chlorine-containing products (NaClO3, NaClO2, and NaCl). NaClO3 was the predominant product, while NaClO2 and NaCl were only detected at the higher temperature of 208 K. The yields of NaClO3 and NaCl increased with absorbed dose, whereas NaClO2 decreased, indicating a dose-dependent formation of oxychlorine species in varying oxidation states during perchlorate decomposition. These findings provide insights into the pathways of perchlorate radiolysis and the temperature- and dose-dependent formation of secondary products relevant to planetary surfaces.