Adsorption of Atmospheric Gases on Pu Surfaces

Abstract

Surface adsorption represents a competition between collision and scattering processes that depend on surface energy, surface structure and temperature. The surface reactivity of the actinides can add additional complexity due to radiological dissociation of the gas and electronic structure. Here we elucidate the chemical bonding of gas molecules adsorbed on Pu metal and oxide surfaces. Atmospheric gas reactions were studied at 190 and 300 K using x-ray photoelectron spectroscopy. Evolution of the Pu 4f and O 1s core-level states were studied as a function of gas dose rates to generate a set of Langmuir isotherms. Results show that the initial gas dose forms Pu 2 O 3 on the Pu metal surface followed by the formation of PuO 2 resulting in a layered oxide structure. This work represents the first steps in determining the activation energy for adsorption of various atmospheric gases on Pu.

Impact of Precipitation Parameters on the Specific Surface Area of PuO2

“…Several studies have analyzed the SSA of the final PuO 2 product with respect to the calcination temperature because of its importance in understanding radiolytic decomposition of water on the PuO 2 surface. − ,− Since the 1960s, the quasi-exponential decrease in the SSA as a function of increasing calcination temperature is thought to be the result of crystalline rearrangement occurring at high temperatures, leading to the disappearance of pores and irregularities on the surface. − A plot of the SRS SSA versus calcination temperature data (Figure ) illustrates that an exponential relationship does not describe the trend over a narrow temperature range. Another interesting observation is that higher calcining temperatures in general led to higher SSA in the data set, which is counterintuitive to higher temperatures leading to decreasing surface areas.…”