Precise molecular orientation determination for adsorbates using x-ray photoelectron diffraction: Methoxy (CH3O) and CO on Cu(110)

Abstract

Using photoelectron diffraction from the 1s states of carbon and oxygen with x-ray excitation, we show that while CO stands perpendicular to a Cu(110) surface, the catalytic intermediate, methoxy, is tilted. The most probable interpretation of the data involves a mixture of two species, one tilted by 18°±3° in the [11¯0] azimuth, and the other tilted by 40°±5° in the [001] azimuth. The origin of this unusual tilt is discussed.