The orientation of formic acid (HCOOH) on ZnO(0001̄)-O and the effect of co-adsorbed Cu have been studied using polarisation dependent C K-edge near edge X-ray absorption fine structure. Formate created by exposure of the substrate to 20 L of HCOOH at 110 K and heating to 340 K is tilted by 55 ± 5° with respect to the surface normal. Pre-adsorbing Cu to create 2D islands covering about half the substrate results in an apparent tilt angle of 32 ± 5° with respect to the surface normal. Since this is close to the magic angle, the apparent tilt could arise from a random orientation of the molecule. The origin of the apparent tilt is likely to be buckling of the Cu(110)-like islands.
- Carboxylic acid
- Low index single crystal surfaces
- Near edge extended X-ray absorption fine structure (NEXAFS)
- Zinc oxide