ZnO<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si8.svg"><mml:mrow><mml:mo>(</mml:mo><mml:mn mathvariant="bold">10</mml:mn><mml:mover><mml:mrow><mml:mn mathvariant="bold">1</mml:mn></mml:mrow><mml:mo stretchy="true">¯</mml:mo></mml:mover><mml:mn mathvariant="bold">0</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math> is unstable in moderate pressures of water

• ZnO( 10 1 ¯ 0 ) was investigated using in situ scanning tunneling microscopy. roughens by formation of steps roughly mbar water. (0001)- and ( 000 )-type are favored over 2 steps. Adsorbed OH H O were measured with X-ray photoelectron spectroscopy. not directly correlated the roughness. A ZnO single crystal microscopy In water surface within minutes. Hereby, 0001 - or -type is The roughened stable ultra-high vacuum does exhibit a different amount hydroxylation adsorbed compared to as-prepared surface. speed roughening related total volume supplied rather than pressure.