THE INTERACTION OF WATER WITH SURFACES OF PT AND IR FIELD EMITTERS

Some results of a study of the adsorption and thermal desorption of H2O on Pt and Ir surfaces, using field emission methods, are presented. At a substrate temperature of 78 K H2O admolecules reduced the total field emission current both from the Pt and Ir tips in a wide range of coverages whereas the local emission current, e.g. from the (001) and (113) faces of Ir, was increased. Water was desorbed from thermally cleaned Pt in the temperature range 140-160 K with an average desorption energy of E(des) = 54 kJ/mol. The possible behavior of H2O molecules on the crystallographically diversified surfaces of Pt and Ir under the conditions of field emission is discussed.