Interaction of Na with multilayer water on MgO(100)

The reaction between Na and multilayer water on MgO(100)/Mo(100) has been s tudied by metastable impact electron spectroscopy (MIES), ultraviolet photo electron spectroscopy (UPS), and temperature-programmed desorption (TPD). A water multilayer was exposed to Na at 100 K. During exposure, an attenuati on of the surface water concentration concomitant with the formation of sur face hydroxyls and metallic Na clusters is observed. After an anneal to 155 K, the metallic Na clusters disappear and the surface hydroxyls are essent ially removed from the outermost surface, leaving water as the dominant sur face species. Further annealing to >170 K leads to massive water and NaOH d esorption, as indicated by TPD. After desorption of all multilayer componen ts the species stabilized at the surface is primarily hydrated NaOH, which is stable up to 530 K.