A unique assignment of both the orientation and the adsorption site of formate (HCOO) on Cu(110) has been made by analysis of near-edge and extended x-ray-absorption fine structure. The species lies with its molecular plane perpendicular to the surface, aligned along the [$1\overline{1}0$] directions, and on top of the copper atoms of the outermost layer; the oxygen atoms almost bridge two copper atoms with an average Cu-O bond length of 1.98±0.07 Å, essentially identical to that in bulk copper formate.

• Received 28 January 1985

DOI:https://doi.org/10.1103/PhysRevLett.54.2250