Gas Adsorption Studies of Ar Molecules on a High-Energy-Beam Irradiated MgO Surface

Abstract

Gas adsorption studies are useful to investigate the fine structure of a surface on an atomic scale. A meso-sized MgO (100) powder surface prepared by using the RF-induction method was irradiated by using an electron beam with energy of 2 MeV. The amount of electron beam dosage was varied from 20 kGy to 1000 kGy. By measuring the Ar gas adsorption data recorded below the triple point (83.78 K), we analyzed the surface changes in the MgO powder before and after the electron beam irradiation. X-ray and TEM investigations revealed that the surface structure was not affected by the irradiation with an electron beam. Calculated values of the 2-dimensional compressibility and the isosteric heat of adsorption coherently showed that a stronger interaction of Ar molecules existed for the electron-irradiated MgO powders than for the pure samples. These results imply the possibility of local surface modification due to bombardments with external electrons.