H2O adsorption on Bi2Sr2CaCu2O8(001).

Photoemission results show that water is physisorbed on a single-crystalline (001) face of the high-temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} at 90 K. A simple model of the electronic structure, in which Bi III lone-pair electrons protrude from the surface, is suggested to account for the stability of this surface ultrahigh vacuum compared with other oxide superconductors.