An EPR study of the surface reactivity of CaO and a comparison with that of MgO

摘要

Two main differences characterize the surface of CaO from that of the homologous widely investigated MgO. The former one is due to the higher basicity of Calcium Oxide which, by the way, is expected on the basis of general considerations and of theoretical calculations. The second, not expected, difference consists in the presence of O~- and O_2~(2-) groups at the surface which trigger a peculiar reactivity of CaO (not observed for MgO) with hydrogen, oxygen and nitric oxide, all leading to the paramagnetic entities (trapped electrons, ozonide ions and NO_3~(2-) radical ions respectively) described in the present paper.